Atlas of the Flora of New England

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Genera - P

Pachysandra
Packera
Paeonia
Palafoxia
Panax
Panicum (see also Dichanthelium, Coleataenia and Urochloa)
Papaver
Pappophorum
Parietaria
Parnassia
Paronychia
Parthenium
Parthenocissus
Pascopyrum
Paspalum
Pastinaca
Patis
Paulownia
Pedicularis
Pellaea
Peltandra
Penstemon
Pentaglottis
Pentaphylloides (see Dasiphora)
Penthorum
Perilla
Periploca
Peritoma
Perovskia
Persicaria
Petasites
Petrorhagia
Petroselinum
Petunia
Peucedanum
Phacelia
Phalaris
Phaseolus
Phedimus
Phegopteris
Phellodendron
Philadelphus
Phleum
Phlox
Phoenix
Photinia (see also Aronia)
Phragmites
Phryma
Phyllodoce
Phyllostachys
Physalis (see also Alkekengi and Leucophysalis)
Physocarpus
Physostegia
Phytolacca
Picea
Picris (see also Helminthotheca)
Pieris
Pilea
Pimpinella
Pinguicula
Pinus
Piptatheropsis
Piptatherum (see Patis)
Piptochaetium
Pistia
Pisum
Pityopsis
Plagiobothrys
Plantago
Platanthera
Platanus
Pluchea
Poa
Podophyllum
Podostemum
Pogonia
Polanisia
Polemonium
Polycarpon
Polygala
Polygaloides (see Polygala)
Polygonatum
Polygonella (See Polygonum)
Polygonum (see also Bistorta, Fallopia and Persicaria)
Polymnia
Polypodium
Polypogon
Polystichum
Pontederia
Populus
Porteranthus (see Gillenia Portulaca
Potamogeton (see also Stuckenia)
Potentilla (see also Comarum, Dasiphora, Drymocallis, Duchesnia and Sibbaldiopsis)
Poteridium
Poterium
Prenanthes (See Nabalus)
Primula
Proboscidea
Proserpinaca
Prunella
Prunus
Pseudabutilon
Pseudognaphalium
Pseudolycopodiella
Pseudolysimachion (See Veronica)
Pseudosasa
Pseudotsuga
Psilocarya (see Rhynchospora)
Ptelea
Pteretis (See Matteuccia)
Pteridium
Pterospora
Ptilimnium
Puccinellia (see also Torreyochloa)
Pueraria
Pulmonaria
Pulsatilla
Pycnanthemum
Pyrola (see also Orthilia)
Pyrus (see also Aronia, Malus, (see also X Sorbaronia) and Sorbus)


PACHYSANDRA (Family: Buxaceae)


PACHYSANDRA TERMINALIS Siebold & Zuccarini - Japanese Pachysandra. 2n = 24, 48.


Roadsides, railroads, waste places, woodland margins, open woodlands. From eastern Asia.



PACKERA (Family: Asteraceae)


Packera anonyma (Alph. Wood) W.A.; Weber & Á. Löve - Small's Ragwort. 2n = 44.


Upland woods. [Senecio smallii Britton]


Packera aurea (Linnaeus) Á. Löve & D. Löve - Golden Ragwort. 2n = 44, (46), (66), (132).


Swamps, low, wet woods, brooksides, springs, stream banks, meadows, moist roadsides. [Senecio aureus Linnaeus var. aureus; S. aureus var. aquilonius Fernald; S. aureus var. gracilis (Pursh) Hooker; S. aureus var. intercursus Fernald]


Packera obovata (Muhlenberg ex Willdenow) W.A. Weber & Á. Löve - 2n = 44, (88), (90).


Fields, woods, stream banks, rocky slopes, in calcareous soil. [Senecio obovatus Muhlenberg ex Willdenow]


Packera paupercula (Michaux) Á. Löve & D. Löve - Balsam Groundsel. 2n = (40), 44, 46, (64), (88), (92).


Stream banks, rocky, open outcrops, slopes and woods. [Senecio gaspensis Greenman; S. pauperculus Michaux var. pauperculus; S. pauperculus var. balsamitae (Muhlenberg ex Willdenow) Fernald; S. pauperculus var. praelongus (Greenman) House]


Packera schweinitziana (Nuttall) W.A. Weber & Á. Löve - 2n = 44, 46.


Meadows, shores, swamps, thickets, fields, roadside ditches. [Senecio robbinsii Oakes ex Rusby]



PAEONIA (Family: Paeoniaceae)


PAEONIA LACTIFLORA Pallas - Chinese Peony. 2n = 10.


Waste places, old house sites. From eastern Asia.


PAEONIA OFFICINALIS Linnaeus - Garden Peony. 2n = 20.


Old fields and orchards. From Europe.



PALAFOXIA (Family: Asteraceae)


PALAFOXIA TEXANA de Candolle - 2n = (20), 22.


Riverbanks. From farther south.



PANAX (Family: Araliaceae)


Panax quinquefolius Linnaeus - Ginseng. 2n = (44), 48.


Rich woodlands.


Panax trifolius Linnaeus - Dwarf Ginseng. 2n = 24.


Rich, moist woodlands.



PANICUM (Family: Poaceae)


Panicum amarum Elliott var. amarum - . 2n = 36.


Sandy coasts.


Panicum amarum var. amarulum (Hitchcock & Chase) P. Palmer - . 2n = ?


Sea beaches. [P. amarulum Hitchcock & Chase]


Panicum capillare Linnaeus - Witchgrass. 2n = 18.


Open sandy or stony soil, roadsides, waste places. [P. capillare var. agreste Gattinger; P. capillare var. occidentale Rydberg]


Panicum dichotomiflorum Michaux subsp. dichotomiflorum - Fall Panicum. 2n = (36), 54.


Moist soil, shores, roadsides, railroads, waste areas. [P. dichotomiflorum var. geniculatum (Alph. Wood) Fernald]


Panicum dichotomiflorum Michaux subsp. puritanorum (Svenson) Freckmann & Lelong - . 2n = ?


Damp sands, pond margins.


Panicum flexile (Gattinger) Scribner - . 2n = 18.


Shores in calcareous areas.


PANICUM MILIACEUM Linnaeus subsp. MILIACEUM - Broom-corn Millet. 2n = 36, (40), (49), (54), (72).


Roadsides, waste places. From the Old World.


Panicum philadelphicum Bernhardi ex Trinius - . 2n = 18.


Shores, woodlands and borders, roadsides, sandy areas, fields. [P. capillare Linnaeus var. campestre Gattinger; P. gattingeri Nash; P. tuckermanii Fernald]


Panicum verrucosum Muhlenberg - . 2n = 36.


Moist soil, shores.


Panicum virgatum Linnaeus - Switchgrass. 2n = (18), 36, (54), (72), (90).


Dry soil, sandy or gravelly shores, fields. [P. virgatum var. cubense Grisebach; P. virgatum var. spissum Linder]



PAPAVER (Family: Papaveraceae)


PAPAVER DUBIUM Linnaeus - Blindeyes. 2n = (14), (22), 28, 42, (56).


Fields, waste places. From Europe.


PAPAVER RHOEAS Linnaeus - Corn Poppy. 2n = 14, (16), (28), (42).


Waste places, fields. From eastern Mediterranean.


PAPAVER SOMNIFERUM Linnaeus - Opium Poppy. 2n = (18), (20), 22, (23), (25), (32), (36), (44).


Waste places, roadsides, fields. From the Mediterranean.



PAPPOPHORUM (Family: Poaceae)


PAPPOPHORUM VAGINATUM Buckley - . 2n = 60.


Wool waste. From farther south and west. [P. MUCRONULATUM misapplied]



PARIETARIA (Family: Urticaceae)


PARIETARIA JUDAICA Linnaeus - Spreading Pellitory. 2n = 26.


Cracks in sidewalks, ballast piles, waste heaps; usually around seaports. From the Mediterranean.


Parietaria pensylvanica Muhlenberg ex Willdenow - Pennsylvania Pellitory. 2n = 14, 16.


Rich, rocky, calcareous woods, waste places.



PARNASSIA (Family: Celastraceae)


Parnassia glauca Rafinesque - . 2n = 36.


Streambanks, boggy spots, fens, meadows, in wet, calcareous soil.



PARONYCHIA (Family: Caryophyllaceae)


Paronychia argyrocoma (Michaux) Nuttall - Silverling. 2n = ?


Bare, granitic, mountain slopes, ledges. [P. argyrocoma var. albimontana Fernald]


Paronychia canadensis (Linnaeus) Alph. Wood - Smooth Forked Chickweed. 2n = ?


Rich, rocky woods, sandy clearings, waste places.


Paronychia fastigiata (Rafinesque) Fernald var. fastigiata - Hairy Forked Chickweed. 2n = 32, 36.


Dry woods, rocky or sandy openings, waste places.



PARTHENIUM (Family: Asteraceae)


PARTHENIUM HYSTEROPHORUS Linnaeus - Santa Maria. 2n = 34, (36).


Waste places. From Mexico, Central America, Caribbean, South America.


PARTHENIUM INTEGRIFOLIUM Linnaeus - Wild Quinine. 2n = 72.


Waste places. From Mexico, Central America, Caribbean, South America.



PARTHENOCISSUS (Family: Vitaceae)


Parthenocissus quinquefolia (Linnaeus) Planchon - Virginia-creeper. 2n = 40.


Thickets, roadsides, woodlands, rocky banks, stone walls, fences. [P. quinquefolia var. hirsuta (Pursh) Planchon; P. inserta (A. Kerner) Fritsch]


PARTHENOCISSUS TRICUSPIDATA (Siebold & Zuccarini) Planchon - Boston Ivy. 2n = 40.


Roadsides, fields, woodland margins, old walls. From eastern Asia.


Parthenocissus vitacea (Knerr) Hitchcock - Thicket-creeper. 2n = 40.


Thickets, streambanks roadsides, woodlands, rocky banks. [P. inserta misapplied]



PASCOPYRUM (Family: Poaceae)


PASCOPYRUM SMITHII (Rydberg) Barkworth & D.R. Dewey - Western Wheatgrass. 2n = (28), (42), 56.


Railroads. From farther west. [AGROPYRON SMITHII Rydberg; ELYTRIGIA SMITHII (Rydberg) Nevski]



PASPALUM (Family: Poaceae)


Paspalum laeve Michaux - . 2n = 40, 70, 58.


Meadows, shores, damp, sandy fields. [P. laeve var. circulare (Nash) W. Stone ex Fernald; P. laeve var. pilosum Scribner; P. circulare Nash; P. longipilum Nash]


Paspalum setaceum Michaux var. setaceum - . 2n = 40.


Sandy fields.


Paspalum setaceum Michaux var. muhlenbergii (Nash) D.J. Banks - . 2n = 20, 40.


Dry fields, pastures. [P. ciliatifolium Michaux var. muhlenbergii (Nash) Fernald; P. pubescens Muhlenberg]


Paspalum setaceum Michaux var. psammophilum (Nash ex Hitchcock) D.J. Banks - . 2n = 40, 60.


Dry, sandy fields near the coast. [P. psammophilum Nash ex Hitchcock]



PASTINACA (Family: Apiaceae)


PASTINACA SATIVA Linnaeus - Parsnip. 2n = 22.


Roadsides, waste places, fields. From Eurasia.



PATIS (Family: Poaceae)


Patis racemosa (Smith) Romaschenko, P.M. Peterson & Soreng - Black Mountain-rice. 2n = 46.


Dry, often calcareous, rocky woods. [Oryzopsis racemosa (Smith) Ricker ex Hitchcock; Piptatherum racemosum (Smith) Eaton]



PAULOWNIA (Family: Paulowniaceae)


PAULOWNIA TOMENTOSA (Thunberg) Steudel - Princess-tree. 2n = (34), 40.


Waste places, roadsides, woodland margins. From China.



PEDICULARIS (Family: Orobanchaceae)


Pedicularis canadensis Linnaeus - Wood Betony. 2n = 16.


Woods, clearings, fields, meadows, roadsides, rocky shores. [P. canadensis var. dobbsii Fernald]


Pedicularis furbishiae S. Watson - Furbish’s Lousewort. 2n = ?


Along rivers.


Pedicularis lanceolata Michaux - Swamp Lousewort. 2n = 16.


Wet woods, swamps, meadows, shores and other wet ground.



PELLAEA (Family: Pteridaceae)


Pellaea atropurpurea (Linnaeus) Link - Purple Cliff-brake. 2n = 87, (174).


Dry, exposed, calcareous rocks (occasionally on crumbling mortar), trap rock.


Pellaea glabella Mettenius ex Kuhn subsp. glabella - Smooth Cliff-brake. 2n = (58), 116.


Dry, calcareous rocks and cliffs.



PELTANDRA (Family: Araceae)


Peltandra virginica (Linnaeus) Rafinesque ex Schott - Arrow Arum. 2n = 88, 112.


Shallow water or mud at margins of ponds and streams, swamps, bogs, damp meadows.



PENSTEMON (Family: Plantaginaceae)


PENSTEMON CALYCOSUS Small - . 2n = 96.


Sandy soil in the open, fields, roadsides. From farther south and west.


PENSTEMON CANESCENS (Britton) Britton - . 2n = 16.


Hillsides. From farther south.


PENSTEMON DIGITALIS Nuttall ex Sims - . 2n = 96.


Moist banks and fields, meadows, clearings, roadsides. From farther south and west.


PENSTEMON GRANDIFLORUS Nuttall - . 2n = 16.


Fields, waste places. From farther west.


Penstemon hirsutus (Linnaeus) Willdenow - . 2n = 16.


Dry fields, woods and hillsides, often in rocky soil.


PENSTEMON LAEVIGATUS Aiton - . 2n = 96.


Fields, woods, meadows, rocky shores, sandy banks, roadsides. From farther south.


PENSTEMON PALLIDUS Small - . 2n = 16.


Sandy fields, banks, usually dry, woodland clearings, roadsides. From farther west and south.


PENSTEMON TUBAEFLORUS Nuttall - . 2n = 32.


Meadows, fields, open woods, roadsides. From farther west and south. [P. TUBAEFLORUS var. ACHOREUS Fernald]



PENTAGLOTTIS (Family: Boraginaceae)


PENTAGLOTTIS SEMPERVIRENS (Linnaeus) Tausch ex L.H. Bailey - Green Alkanet. 2n = (16), 22.


Copse near beach. From southwestern Europe.



PENTHORUM (Family: Penthoraceae)


Penthorum sedoides Linnaeus - Ditch-stonecrop. 2n = 16, 18.


Wet, low, open ground, shores, marshes, streambanks.



PERILLA (Family: Lamiaceae)


PERILLA FRUTESCENS (Linnaeus) Britton var. FRUTESCENS - . 2n = (28), (38), 40.


Waste places, roadsides, fields. From southern and eastern Asia. [P. OCYMOIDES Linnaeus]


PERILLA FRUTESCENS (Linnaeus) Britton var. CRISPA (Bentham) W. Deane - . 2n = 40.


Waste places, roadsides. Known only from cultivation.



PERIPLOCA (Family: Apocynaceae)


PERIPLOCA GRAECA Linnaeus - Silk-vine. 2n = 22, 24.


Roadsides, upper part of rocky beach. From Eurasia.



PERITOMA (Family: Cleomaceae)


PERITOMA SERRULATA (Pursh) de Candolle - Rocky Mountain Beeplant. 2n = 32, 34, 60.


Waste places. From farther west. [CLEOME SERRULATA Pursh]



PEROVSKIA (Family: Lamiaceae)


PEROVSKIA ATRIPLICIFOLIA Bentham - . 2n = 20.


Roadsides. From Asia.



PERSICARIA (Family: Polygonaceae)


Persicaria amphibia (Linnaeus) Delarbre - Water Smartweed. 2n = (22), 66, 88, (96), (132).


Shores, shallow waters of streams and ponds. [Polygonum amphibium Linnaeus var. amphibium; P. amphibium var. emersum Michaux; P. amphibium var. stipulaceum N. Coleman; P. coccineum Muhlenberg ex Willdenow]


Persicaria arifolia (Linnaeus) Haraldson - Halberd-leaved Tearthumb. 2n = ?


Swamps, meadows, wet places. [Polygonum arifolium Linnaeus; P. arifolium var. pubescens (R. Keller) Fernald]


Persicaria careyi (Olney) Greene - . 2n = ?


Roadsides, clearings, low thickets, swamps. [Polygonum careyi Olney]


PERSICARIA EXTREMIORIENTALIS (Voroschilov) Tzvelev - . 2n = ?


Roadsides, waste places. From China, Korea, Japan.


PERSICARIA HYDROPIPER (Linnaeus) Delarbre - Common Smartweed. 2n = (18), 20, (22), (24).


Moist or wet soils, especially in weedy places. From Europe. [POLYGONUM HYDROPIPER Linnaeus]


Persicaria hydropiperoides (Michaux) Small - Swamp Smartweed. 2n = ?


Shallow water, shores, marshes, swamps, swales. [Polygonum hydropiperoides Michaux; P. opelousanum Riddell ex Small var. opelousanum; P. opelousanum var. adenocalyx Stanford]


Persicaria lapathifolia (Linnaeus) Delarbre - Pale Smartweed. 2n = 22, (24), (44).


Swampy thickets, shores, damp clearings, ditches, fields, roadsides, waste places. [Polygonum lapathifolium Linnaeus var. lapathifolium; P. lapathifolium var. prostratum Wimmer; P. lapathifolium var. salicifolium Sibthorp; P. scabrum Moench]


PERSICARIA LONGISETA (Bruijn) Kitagawa - Creeping Smartweed. 2n = 40.


Moist roadsides, waste places, shores. From eastern Asia. [POLYGONUM CAESPITOSUM Blume var. LONGISETUM (Bruijn) Steward]


PERSICARIA MACULOSA (Sibthorp) Gray - Lady's-thumb. 2n = 20, 22, 40, 42, 44.


Roadsides, waste places, damp clearings, shores. From Eurasia. [POLYGONUM DUBIUM Stein ex A. Braun; P. PERSICARIA Linnaeus var. PERSICARIA; P. PERSICARIA var. RUDERALE Meisner; P. PURITANORUM Fernald]


PERSICARIA MINOR (Hudson) Opiz - Small Water-pepper. 2n = 40.


Roadsides, ditches, damp, open places. From Europe. [POLYGONUM MINUS Hudson; P. MINUS var. SUBCONTINUUM (Meisner) Fernald]


PERSICARIA NEPALENSIS (Meisner) H. Gross - . 2n = 48.


Waste places. From Asia. [POLYGONUM NEPALENSE Meisner]


PERSICARIA ORIENTALIS (Linnaeus) Spach - Kiss-me-over-the-garden-gate. 2n = 22.


Moist, waste places, roadsides, fields. From Asia. [POLYGONUM ORIENTALE Linnaeus]


Persicaria pensylvanica (Linnaeus) M. Gómez - Pinkweed. 2n = 22, 88.


Shores, thickets, clearings, ditches, waste places, in moist soil. [Polygonum pensylvanicum Linnaeus var. pensylvanicum; P. pensylvanicum var. laevigatum Fernald; P. pensylvanicum var. nesophilum Fernald]


PERSICARIA PERFOLIATA (Linnaeus) H. Gross - Devil's-tail Tearthumb. 2n = ?


Roadsides, waste places. From Asia. [POLYGONUM PERFOLIATUM (Linnaeus) Linnaeus]


Persicaria punctata (Elliott) Small - Dotted Smartweed. 2n = 44.


Wet, often sandy, soil, shores, marshes. [Polygonum punctatum Elliott var. punctatum; P. punctatum var. confertiflorum (Meisner) Fassett; P. punctatum var. leptostachyum (Meisner) Small; P. punctatum var. parvum Marie-Victorin & J. Rousseau]


Persicaria puritanorum (Fernald) Soják - . 2n = ?


Sandy or gravelly pond shores. [P. puritanorum Fernald]


Persicaria robustior (Small) E.P. Bicknell - . 2n = ?


Shores, swamps, often in water. [Polygonum robustius (Small) Fernald]


Persicaria sagittata (Linnaeus) H. Gross - Arrow-vine. 2n = 40.


Swamps, meadows, moist, low ground. [Polygonum sagittatum Linnaeus]


Persicaria setacea (Baldwin) Small - Swamp Smartweed. 2n = 20.


Shores, alluvial woods, swamps. [Polygonum setaceum Baldwin var. interjectum Fernald]


Persicaria virginiana (Linnaeus) Gaertner - Jumpseed. 2n = 44, ca. 48.


Shaded, rich soil. [Polygonum virginianum Linnaeus; Tovara virginiana (Linnaeus) Rafinesque]


PERSICARIA WALLICHII Greuter & Burdet var. WALLICHII - Himalayan Knotweed. 2n = 22.


Moist, waste places. From Asia. [POLYGONUM POLYSTACHYUM Wallich ex Meisner]


Persicaria hybrid

Persicaria hydropiperoides (Michaux) Small X P. robustior (Small) E.P. Bicknell - .





PETASITES (Family: Asteraceae)


Petasites frigidus (Linnaeus) Fries var. palmatus (Aiton) Cronquist - Sweet Coltsfoot. 2n = 60, (61), (62).


Swampy woods, streambanks, damp clearings, roadside ditches. [P. palmatus (Aiton) A. Gray]


PETASITES HYBRIDUS (Linnaeus) G. Gaertner, B. Meyer & Scherbius - Butterbur. 2n = 60.


Brooksides, waste places. From Eurasia.



PETRORHAGIA (Family: Caryophyllaceae)


PETRORHAGIA PROLIFERA (Linnaeus) P.W. Ball & Heywood - Childing Pink. 2n = (20), 30, (60).


Roadsides, ballast, fields. From Eurasia.


PETRORHAGIA SAXIFRAGA (Linnaeus) Link var. SAXIFRAGA - Tunic-flower. 2n = 30, 60.


Roadsides, sandy, waste places. From Eurasia.



PETROSELINUM (Family: Apiaceae)


PETROSELINUM CRISPUM (Miller) Fuss - Common Parsley. 2n = 22.


Waste places, fields. From the Mediterranean region.



PETUNIA (Family: Solanaceae)


PETUNIA AXILLARIS (Lamarck) Britton, Sterns & Poggenburg - White Moon Petunia. 2n = 14, (21), (56).


Roadsides, railroads, waste places. From South America.


PETUNIA INTEGRIFOLIA (Hooker) Schinz & Thellung - Violet Petunia. 2n = 14.


Waste places, roadsides. From South America. [P. VIOLACEA Lindley - illegitimate name]


Petunia hybrid

PETUNIA X ATKINSIANA (Sweet) D. Don ex W.H. Baxter - .



[P. AXILLARIS (Lamarck) Britton, Sterns & Poggenburg X P. INTEGRIFOLIA (Hooker) Schinz & Thellung; P. X HYBRIDA misapplied ]



PEUCEDANUM (Family: Apiaceae)


PEUCEDANUM PALUSTRE (Linnaeus) Moench - Milk-parsley. 2n = 22.


Meadows, damp fields, swampy thickets. From Eurasia.



PHACELIA (Family: Hydrophyllaceae)


PHACELIA BRACHYLOBA (Bentham) A. Gray - . 2n = 24.


Wool waste, waste places. From California, Baja Mexico.


PHACELIA DISTANS Bentham - . 2n = 22, 24.


Wool waste. From southwestern United States, Baja Mexico.


PHACELIA EGENA (Brand) Greene ex J.T. Howell - . 2n = 22.


Wool waste. From California. [P. MAGELLANICA (Lamarck) R. Brown ex Sweet (in part)]


PHACELIA MINOR (Harvey) Thellung ex F. Zimmerman - . 2n = ?


Wool waste. From California, Baja Mexico.



PHALARIS (Family: Poaceae)


Phalaris arundinacea Linnaeus var. arundinacea - Reed Canary-grass. 2n = (14), 28, (35), (42), (48).


Shores, wet meadows.


PHALARIS CANARIENSIS Linnaeus - Canary-grass. 2n = 12.


Roadsides, railroads, waste places. From Europe.



PHASEOLUS (Family: Fabaceae)


PHASEOLUS COCCINEUS Linnaeus - Scarlet Runner. 2n = 22.


Roadsides, waste places. From Mexico, Central America. [P. MULTIFLORUS Lamarck - illegitimate name]


Phaseolus polystachios (Linnaeus) Britton, Sterns & Poggenburg var. polystachios - Wild Bean. 2n = 22.


Rocky woods, dry, wooded ledges, roadsides. [P. polystachios var. aquilonius Fernald]


PHASEOLUS VULGARIS Linnaeus - Common Bean. 2n = 22, (44).


Waste places, roadsides. From Mexico, Central and South America. [P. VULGARIS var. HUMILIS Alefeld -- invalid name]



PHEDIMUS (Family: Crassulaceae)


PHEDIMUS AIZOON (Linnaeus) 't Hart - . 2n = 30-32, 48, 56, 61, 63, 64, 66, 78, 80, 84, 85, 88, 93-97, 102.


Open, rocky places. From eastern and northern Asia. [SEDUM AIZOON Linnaeus]


PHEDIMUS SPURIUS (M. Bieberstein) 't Hart - Caucasian Stonecrop. 2n = 28, 42.


Rocky or sandy roadsides, waste places, old fields. [SEDUM SPURIUM M. Bieberstein; S. STOLONIFERUM - misapplied]



PHEGOPTERIS (Family: Thelypteridaceae)


Phegopteris connectilis (Michaux) Watt - Long Beech Fern. 2n = (60), 90, (120), (180).


Rich, damp woods, cool, shaded, rocky banks, moist cliffs. [Dryopteris phegopteris (Linnaeus) C. Christensen; Thelypteris phegopteris (Linnaeus) Slosson]


Phegopteris hexagonoptera (Michaux) Fée - Broad Beech Fern. 2n = 60, (120).


Rich woods and thickets. [Dryopteris hexagonoptera (Michaux) C. Christensen; Thelypteris hexagonoptera (Michaux) Weatherby]



PHELLODENDRON (Family: Rutaceae)


PHELLODENDRON AMURENSE Ruprecht - Amur Corktree. 2n = 28, ca. 66, 76, 78, ca. 80.


Woodlands, roadsides, swamps, pond shores. From eastern Asia. [P. JAPONICUM Maximowicz; P. SACHALINENSE (F. Schmidt) Sargent]



PHILADELPHUS (Family: Hydrangeaceae)


PHILADELPHUS CORONARIUS Linnaeus - Sweet Mock-orange. 2n = 26.


Woodlands, roadside thickets, woodland margins. From Eurasia. [P. CAUCASICUS Koehne]


PHILADELPHUS INCANUS Koehne - . 2n = 26.


Margins of rich woodlands. From China.


PHILADELPHUS INODORUS Linnaeus - . 2n = 26.


Woodland margins, roadsides. From southeastern United States. [P. INODORUS var. GRANDIFLORUS (Willdenow) A. Gray]


PHILADELPHUS PUBESCENS Loiseleur - . 2n = 26.


Waste places, streambanks, deciduous woodlands, thickets. From farther west and south. [P. PUBESCENS var. VERRUCOSUS (Schrader ex de Candolle) S.Y. Hu]


Philadelphus hybrids

PHILADELPHUS X NIVALIS Jacques - .


[P. CORONARIUS Linnaeus X P. PUBESCENS Loiseleur]


PHILADELPHUS X POLYANTHUS Rehder - .


[P. CORONARIUS Linnaeus X ?]


PHILADELPHUS X VIRGINALIS Rehder - .


[unknown parentage]



PHLEUM (Family: Poaceae)


Phleum alpinum Linnaeus subsp. alpinum - Mountain Timothy. 2n = 14, 28.


High altitudes.


PHLEUM ARENARIUM Linnaeus - . 2n = 14.


Waste areas, ballast. From Europe and North Africa.


PHLEUM PRATENSE Linnaeus subsp. PRATENSE - Timothy. 2n = (14), (21), (28), 42, (63).


Fields, roadsides. From Eurasia. [P. PRATENSE var. NODOSUM (Linnaeus) Hudson]


PHLEUM SUBULATUM (Savi) Ascherson & Graebner - . 2n = 14.


Waste areas, ballast. From the Mediterranean.



PHLOX (Family: Polemoniaceae)


PHLOX BIFIDA L.C. Beck subsp. BIFIDA - Sand Phlox. 2n = 14.


Shaded, sandy soil near cemetery. From farther west.


Phlox divaricata Linnaeus subsp. divaricata - Wild Blue Phlox. 2n = 14.


Damp, rocky, rich woodlands, waste places.


Phlox maculata Linnaeus subsp. maculata - Wild Sweet William. 2n = 14.


Meadows, alluvial woodlands, streambanks, swamps, roadsides.


PHLOX PANICULATA Linnaeus - Fall Phlox. 2n = 14.


Roadsides, woodland margins, fields, thickets. From farther west and south.


Phlox pilosa Linnaeus subsp. pilosa - . 2n = 14, (28).


Moist, grassy banks, dry knolls.


PHLOX STOLONIFERA Sims - Creeping Phlox. 2n = 14.


Cemeteries, roadsides. From farther south.


PHLOX SUBULATA Linnaeus subsp. SUBULATA - Moss Phlox. 2n = 14, 28.


Cemeteries, sandy fields and roadsides, waste places. From farther west and south.


Phlox hybrid

PHLOX X PROCUMBENS Lehmann (pro species) - .


[P. STOLONIFERA Sims X P. SUBULATA Linnaeus]



PHOENIX (Family: Arecaceae)


PHOENIX DACTYLIFERA Linnaeus - Date Palm. 2n = 28, (34), 36, (40).


Waste places. Probably from the Middle East.



PHOTINIA (Family: Rosaceae)


PHOTINIA VILLOSA (Thunberg) de Candolle - Oriental Photinia. 2n = 34.


Swamps, woodlands. From eastern Asia.



PHRAGMITES (Family: Poaceae)


PHRAGMITES AUSTRALIS (Cavanilles) Steudel subsp. AUSTRALIS - Common Reed. 2n = 36, (42), (44), (46), 48, (49-54), 72, (84), 96, (120).


Marshes, shores, ditches. From Eurasia. [P. COMMUNIS Trinius var. COMMUNIS; P. communis var. berlandieri misapplied]


Phragmites australis (Cavanilles) Steudel subsp. americanus Saltonstall, P.M. Peterson, & Soreng - Common Reed. 2n = ?


Marshes, shores, ditches. [P. COMMUNIS Trinius var. COMMUNIS misapplied; P. communis var. berlandieri misapplied]



PHRYMA (Family: Phrymaceae)


Phryma leptostachya Linnaeus var. leptostachya - Lopseed. 2n = (14),28.


Rich, deciduous woods, usually moist.



PHYLLODOCE (Family: Ericaceae)


Phyllodoce caerulea (Linnaeus) Babington - Mountain-heath. 2n = 24.


Alpine rocks and peat.



PHYLLOSTACHYS (Family: Poaceae)


PHYLLOSTACHYS DULCIS McClure - Sweetshoot Bamboo. 2n = 48.


Field margin. From China.


PHYLLOSTACHYS NIGRA (Loddiges ex Lindley) Munro var. NIGRA - Black Bamboo. 2n = 48, 54.


Roadsides. From China.



PHYSALIS (Family: Solanaceae)


PHYSALIS ANGULATA Linnaeus - . 2n = (24), 48.


Waste places. From farther west and south.


Physalis grisea (Waterfall) M. Martínez - Strawberry-tomato. 2n = 24.


Waste places, roadsides, sandy fields and bluffs. [P. pruinosa misapplied; P. pubescens Linnaeus var. grisea Waterfall]


Physalis heterophylla Nees - Clammy Ground-cherry. 2n = 24.


Fields, dry, open woods, clearings, roadsides, waste places. [P. heterophylla var. ambigua (A. Gray) Rydberg; P. nyctaginea Dunal]


Physalis longifolia Nuttall var. subglabrata (Mackenzie & Bush) Cronquist - . 2n = 24.


Waste places, roadsides, fields. [P. subglabrata Mackenzie & Bush; P. virginiana Miller var. subglabrata (Mackenzie & Bush) Waterfall]


PHYSALIS PHILADELPHICA Lamarck - . 2n = ?


Waste places. From Mexico. [P. PHILADELPHICA var. IMMACULATA misapplied; P. IXOCARPA Brotero ex Hornemann var. IMMACULATA misapplied]


Physalis virginiana Miller - . 2n = 24.


Waste places, fields, dry, sandy or rocky woodlands, woodland margins, clearings.



PHYSOCARPUS (Family: Rosaceae)


PHYSOCARPUS OPULIFOLIUS (Linnaeus) Maximowicz - Eastern Ninebark. 2n = 18.


Rocky banks, shores, thickets, fields, roadsides, waste places. From farther west and south.



PHYSOSTEGIA (Family: Lamiaceae)


Physostegia virginiana (Linnaeus) Bentham subsp. virginiana - Obedient-plant. 2n = (14), 38, (76).


Roadsides, fields, streambanks, damp thickets, shores. [P. virginiana var. granulosa (Fassett) Fernald; P. virginiana var. speciosa (Sweet) A. Gray]



PHYTOLACCA (Family: Phytolaccaceae)


Phytolacca americana Linnaeus var. americana - Pokeweed. 2n = 36.


Clearings, waste places, roadsides, in moist soil.



PICEA (Family: Pinaceae)


PICEA ABIES (Linnaeus) H. Karsten - Norway Spruce. 2n = 24, (48).


Woods, hedgerows. From Europe.    CONN herbarium image


Picea glauca (Moench) Voss - White Spruce. 2n = 24.


Moist woods, dry sandy soils, old pastures, rocky slopes, exposed hilltops, ocean cliffs.    CONN herbarium image


Picea mariana (Miller) Britton, Sterns, & Poggenburg. - Black Spruce. 2n = 24, (40).


Northward on mountain slopes, rocky hillsides, high banks of streams, bogs; southward in sphagnum bogs and swamps.    CONN herbarium image


Picea rubens Sargent - Red Spruce. 2n = 24.


Rocky, well-drained, upland woods, mountain slopes, occasionally in swamps (southward).    CONN herbarium image



PICRIS (Family: Asteraceae)


PICRIS HIERACIOIDES Linnaeus - 2n = 10.


Dry fields, roadsides, waste places. From Eurasia.



PIERIS (Family: Ericaceae)


PIERIS FLORIBUNDA (Pursh) Bentham & Hooker (son) - Mountan Fetterbush. 2n = 24.


Hedgerows.



PILEA (Family: Urticaceae)


Pilea fontana (Lunell) Rydberg - Lesser Clearweed. 2n = ?


Moist to wet, shaded woods, mossy stream borders, springs, swamps.


Pilea pumila (Linnaeus) A. Gray - Richweed. 2n = 24, 26.


Moist, shaded areas.



PIMPINELLA (Family: Apiaceae)


PIMPINELLA ANISUM Linnaeus - Anise. 2n = 18, 20.


Waste places. From eastern Mediterranean region, southwestern Asia.


PIMPINELLA MAJOR (Linnaeus) Hudson - . 2n = (18), 20, (36).


Moist roadsides. From Europe.


PIMPINELLA SAXIFRAGA Linnaeus subsp. SAXIFRAGA - Burnet-saxifrage. 2n = (18), (20), (36), 40.


Moist roadsides. From Europe.



PINGUICULA (Family: Lentibulariaceae)


Pinguicula vulgaris Linnaeus subsp. vulgaris - Common Butterwort. 2n = (32), (50), 64.


Wet rocks, open spots, chiefly at high altitudes.



PINUS (Family: Pinaceae)


Pinus banksiana Lambert - Jack Pine. 2n = (18), 24.


Sterile sand or rocky soils, rocky slopes and ledges, escaped from plantations at roadsides and bog margins (southward).    CONN herbarium image


PINUS MUGO Turra - Swiss Mountain Pine. 2n = 24.


Old pastures. From Europe.    CONN herbarium image


PINUS NIGRA J.F. Arnold - Austrian Pine. 2n = (18), 24.


Woodland margins. From Eurasia, northern Africa.


Pinus resinosa Aiton - Red Pine. 2n = 24.


Sandy or gravelly soil in dry woods and barrens, mountain slopes, ledges, occasionally in peat bogs.    CONN herbarium image


Pinus rigida Miller - Pitch Pine. 2n = 24.


Dry, sterile, sandy or gravelly soils, rocky slopes, occasionally in cold swamps and bogs.    CONN herbarium image


Pinus strobus Linnaeus - Eastern White Pine. 2n = 24.


Sandy or fertile, well-drained soils, but tolerating wet ground (rarely in bogs).    CONN herbarium image


PINUS SYLVESTRIS Linnaeus var. SYLVESTRIS - Scots Pine. 2n = 24, (36), (48).


Roadsides, fallow fields, dry woods. From Eurasia.    CONN herbarium image


PINUS THUNBERGII Parlatore - Japanese Black Pine. 2n = 24, (48).


Dry sandy soils. From eastern Asia.    CONN herbarium image



PIPTATHEROPSIS (Family: Poaceae)


Piptatheropsis canadensis (Poiret) Romaschenko, P.M. Peterson & Soreng - . 2n = 22.


Dry, sandy or rocky woods. [Oryzopsis canadensis (Poiret) Torrey]


Piptatheropsis pungens (Torrey ex Sprengel) Romaschenko, P.M. Peterson & Soreng - . 2n = 22, 24.


Dry, sandy or rocky woods. [Oryzopsis pungens (Torrey ex Sprengel) Hitchcock]



PIPTOCHAETIUM (Family: Poaceae)


Piptochaetium avenaceum (Linnaeus) Parodi - Black Oat-grass. 2n = 22.


Dry openings, open woods. [Stipa avenacea Linnaeus]



PISTIA (Family: Araceae)


PISTIA STRATIOTES Linnaeus - Water-lettuce. 2n = (14), 28.


Ponds, rivers, lakes. From tropical Africa, Asia, Australia, South America, Central America, Mexico.



PISUM (Family: Fabaceae)


PISUM SATIVUM Linnaeus var. SATIVUM - Garden Pea. 2n = 14, (28), (30), (56), (112).


Roadsides, waste places, fields, railroads. From Eurasia, northern Africa.



PITYOPSIS (Family: Asteraceae)


Pityopsis falcata (Pursh) Nuttall - 2n = 18.


Dry, sandy, open soil, railroads. [Chrysopsis falcata (Pursh) Elliott]



PLAGIOBOTHRYS (Family: Boraginaceae)


PLAGIOBOTHRYS RETICULATUS (Piper) I.M. Johnston - . 2n = ?


Wool waste. From western North America.



PLANTAGO (Family: Plantaginaceae)


PLANTAGO ARENARIA Waldstein & Kitaibel - . 2n = 12, (24).


Waste places, roadsides, railroads, fields. From Eurasia, northern Africa. [P. INDICA Linnaeus; P. PSYLLIUM Linnaeus -- rejected name]


Plantago aristata Michaux - Bracted Plantain. 2n = 20.


Open, sterile or sandy, disturbed soil, gravel, roadsides, fields, waste places.


PLANTAGO CORONOPUS Linnaeus - Buck’s-horn Plantain. 2n = 10, (11), (20), (30), (31).


Waste places. From Eurasia, northern Africa.


PLANTAGO LANCEOLATA Linnaeus - Ribgrass. 2n = 12, (13), (14), (24), (96).


Fields, roadsides, waste places. From Eurasia, northern Africa. [P. LANCEOLATA var. SPHAEROSTACHYA Mertens & W.D.J. Koch; P. ALTISSIMA misapplied]


PLANTAGO MAJOR Linnaeus - Common Plantain. 2n = (6), 12, (24), (32).


Roadsides, waste places, disturbed soil. From Eurasia. [P. MAJOR var. PILGERI Domin; P. MAJOR var. SCOPULORUM Fries & Broberg; P. INTERMEDIA Gilibert]


Plantago maritima Michaux - Seaside Plantain. 2n = (6), 12, (18), (24), (36).


Salt marshes, beaches, coastal rocks. [P. maritima var. juncoides (Lamarck) A. Gray; P. juncoides Lamarck var. decipiens (Barnéoud) Fernald; P. juncoides var. glauca (Hornemann) Fernald; P. oliganthos Roemer & Schultes var. oliganthos; P. oliganthos var. fallax Fernald]


PLANTAGO MEDIA Linnaeus - Hoary Plantain. 2n = (12), 24.


Fields, roadsides, waste places. From Eurasia.


PLANTAGO PATAGONICA Jacquin - . 2n = 20, (24).


Railroads, fields, waste places. From farther west, southern South America. [P. PURSHII Roemer & Schultes]


Plantago pusilla Nuttall - . 2n = 12.


Dry, sandy roadsides, fields, railroads and clearings, dry ledges.


Plantago rugelii Decaisne - . 2n = 24.


Roadsides, wood roads, waste places, meadows, shores, fields.


Plantago virginica Linnaeus - Pale-seed Plantain. 2n = 24.


Fields, ledges, open, gravelly, rocky or sandy soil, often dry.



PLATANTHERA (Family: Orchidaceae)


Platanthera aquilonis Sheviak - Northern Green Orchis. 2n = 42.


Springy woods, sphagnum bogs, ditches. [P. hyperborea misapplied; Habenaria hyperborea misapplied]

Platanthera blephariglottis (Willdenow) Lindley var. blephariglottis - White Fringed Orchis. 2n = 42.


Sphagnum bogs, wet, sphagnous soil. [Habenaria blephariglottis (Willdenow) Hooker]


Platanthera ciliaris (Linnaeus) Lindley - Yellow Fringed Orchis. 2n = ?


Swampy woods, wet thickets, bogs. [Habenaria ciliaris (Linnaeus) R. Brown]


Platanthera clavellata (Michaux) Luer - Green Woodland Orchis. 2n = 42.


Swampy woods, bogs, spring-heads, shores, typically sphagnous. [Habenaria clavellata (Michaux) Sprengel; H. clavellata var. ophioglossoides Fernald]


Platanthera cristata (Michaux) Lindley - Crested Yellow Orchis. 2n = 42.


Damp, acid woods, low moist meadows. [Habenaria cristata (Michaux) R. Brown]


Platanthera dilatata (Pursh) Lindley ex L.C. Beck var. dilatata - Bog Candle. 2n = 42.


Springy woods, bogs, shores, meadows. [Habenaria dilatata (Pursh) Hooker]


Platanthera flava (Linnaeus) Lindley var. herbiola (R. Brown) Luer - Tubercled Orchis. 2n = 42.


Springy meadows, shores. [Habenaria flava (Linnaeus) R. Brown ex Sprengel var. herbiola (R. Brown) Ames & Correll]


Platanthera grandiflora (Bigelow) Lindley - Large Purple Fringed Orchis. 2n = 42.


Rich, swampy woods, spring-heads, along streams, thickets. [Habenaria fimbriata (Aiton) R. Brown;  H. psycodes (Linnaeus) Sprengel var. grandiflora (Bigelow) A. Gray]


Platanthera hookeri (Torrey ex A. Gray) Lindley - Hooker's Orchis. 2n = 42.


Rich, dry woods. [Habenaria hookeri Torrey ex A. Gray]


Platanthera huronensis (Nuttall) Lindley - . 2n = 84.


Springy woods, sphagnum bogs, ditches. [P. hyperborea var. huronensis (Nuttall) Luer; P. X media (Rydberg) Luer; Habenaria hyperborea (Linnaeus) R. Brown var. huronensis (Nuttall) Farwell]


Platanthera lacera (Michaux) G. Don - Ragged Orchis. 2n = 42.


Meadows, damp fields, alluvial or wet woods. [Habenaria lacera (Michaux) R. Brown ex Sprengel]


Platanthera leucophaea (Nuttall) Lindley - Prairie Fringed Orchis. 2n = 42.


Bogs, open tamarack swamps. [Habenaria leucophaea (Nuttall) A. Gray]


Platanthera macrophylla P.M. Brown - . 2n = ?


Rich woods. [P. orbiculata (Pursh) Lindley var. macrophylla (Goldie) Luer; Habenaria macrophylla Goldie; H. orbiculata (Pursh) Hooker var. macrophylla (Goldie) B. Boivin]


Platanthera obtusata (Banks ex Pursh) Lindley - Blunt-leaf Orchis. 2n = 42, (63), (126).


Sphagnum bogs, damp woods, especially coniferous or mixed. [Habenaria obtusata (Banks ex Pursh) Richardson]


Platanthera orbiculata (Pursh) Lindley - Round-leaved Orchis. 2n = 42.


Rich woods. [Habenaria orbiculata (Pursh) Hooker]


Platanthera psycodes (Linnaeus) Lindley - Small Purple Fringed Orchis. 2n = 42.


Wet woods, damp thickets, along streams. [Habenaria psycodes (Linnaeus) Sprengel]


Platanthera hybrids

Platanthera X andrewsii (M. White) Luer - .


[P. lacera (Michaux) G. Don X P. psycodes (Linnaeus) Lindley]


Platanthera dilatata (Pursh) Lindley ex L.C. Beck X P. huronensis (Nuttall) Lindley - .


[P. X media misapplied]


Platanthera grandiflora (Bigelow) Lindley X P. lacera (Michaux) G. Don - .



[P. X keenanii P.M. Brown - illegitimate name]


Platanthera grandiflora (Bigelow) Lindley X P. psycodes (Linnaeus) Lindley - .


[P. X enigma P.M. Brown - invalid name]



PLATANUS (Family: Platanaceae)


Platanus occidentalis Linnaeus - Sycamore. 2n = 42.


Rich soil, especially along streams.



PLUCHEA (Family: Asteraceae)


Pluchea odorata (Linnaeus) Cassini var. succulenta (Fernald) Cronquist - Saltmarsh Fleabane. 2n = ?


Salt marshes, sandy shores of coastal ponds, tidal flats. [P. purpurascens (Swartz) de Candolle var. succulenta Fernald; P. camphorata - miapplied]



POA (Family: Poaceae)


Poa alsodes A. Gray - . 2n = ?


Alluvial woods.


POA ANNUA Linnaeus - Annual Bluegrass. 2n = (14), (24-26), 28, (42), (52).


Roadsides, fields, waste places. From Eurasia.


POA BULBOSA Linnaeus subsp. BULBOSA - Bulbous Bluegrass. 2n = 28, 42, 45.


Dry fields. From Eurasia.


POA CHAPMANIANA Scribner - . 2n = ?


Fields, weedy places. From farther south and west.


POA COMPRESSA Linnaeus - Canada Bluegrass. 2n = (14), (35), 42, (49), (50), (56), (84).


Dry soil, roadsides, waste places. From Eurasia.


Poa glauca Vahl subsp. glauca - . 2n = 42, 56, (63), (65), 70.


Alpine meadows and ravines.


POA INTERIOR Rydberg - . 2n = 42.


Cliffs, bluffs, calcareous headlands, shores. From farther west.


Poa laxa Haenke subsp. fernaldiana (Nannfeldt) Hylander - . 2n = 42.


Alpine meadows. [P. fernaldiana Nannfeldt]


POA NEMORALIS Linnaeus var. NEMORALIS - Wood Bluegrass. 2n = 28, 33, 42, 43, 56.


Dry woods, roadsides. From Europe.


Poa palustris Linnaeus - Fowl Meadow-grass. 2n = (14), (21), 28, (29), (30), (42).


Moist woods, shores, swamps, meadows.


POA PRATENSIS Linnaeus subsp. PRATENSIS - Kentucky Bluegrass. 2n = 28, 42, 43, 44, 48, 49, 50, 51, 52, 54, 56, 58, 59, 62, 65, 66, 67, 74, ca. 85, ca. 86, 88, 89, 90, 95.


Roadsides, fields, meadows. From Europe.


Poa pratensis Linnaeus subsp. alpigena (Lindman) Hiitonen - . 2n = 28, 32, 35, 42, 43, 48, 50, 53, 56, 60, 63, 64, 65, 67, 68, 69, 70, 72, 73, 74, 76, 77, 78, 79, 82, 83, 84, 86, 88, 89, 92, 94.


Alpine regions. [P. alpigena Lindman; P. arctica - misapplied]


POA PRATENSIS Linnaeus subsp. ANGUSTIFOLIA (Linnaeus) Dumortier - . 2n = 28, 30, 42, 46, 48-54, 56, 57, 59-66, 68, 70, 72, 83.

Dry soil in the open. From Europe. [P. ANGUSTIFOLIA Linnaeus] This taxon is not mapped since we did not distinguish between the subspecies PRATENSIS and ANGUSTIFOLIA of P. PRATENSIS when we recorded specimen data.


Poa saltuensis Fernald & Wiegand subsp. saltuensis - . 2n = 28.


Rich, usually dry, woods. [P. saltuensis var. microlepis Fernald]


Poa saltuensis Fernald & Wiegand subsp. languida (Hitchcock) A. Haines - . 2n = ?


Rich, usually dry, rocky woods, cliffs. [P. debilis Torrey - illegitimate name; P. languida Hitchcock]


POA TRIVIALIS Linnaeus subsp. TRIVIALIS - Rough Bluegrass. 2n = 14, (28), (72).


Springheads, brook sides, glades. From Eurasia.



PODOPHYLLUM (Family: Berberidaceae)


PODOPHYLLUM PELTATUM Linnaeus - Mayapple. 2n = 12, (16), (24).


Moist roadsides, moist fields, meadows, rich woods. From farther south and west, but some populations possibly native.



PODOSTEMUM (Family: Podostemaceae)


Podostemum ceratophyllum Michaux - Threadfoot. 2n = ?


On rocks in rapid current of streams.



POGONIA (Family: Orchidaceae)


Pogonia ophioglossoides (Linnaeus) Ker Gawler - Rose Pogonia. 2n = 18.


Sphagnum bogs, swamps, wet meadows, pond shores, sphagnous thickets.



POLANISIA (Family: Cleomaceae)


Polanisia dodecandra (Linnaeus) de Candolle subsp. dodecandra - Clammyweed. 2n = 20, 22.


Sandy or gravelly shores. [P. graveolens Rafinesque]


POLANISIA DODECANDRA (Linnaeus) de Candolle subsp. TRACHYSPERMA (Torrey & A. Gray) Iltis - Sandyseed. 2n = 20.


Roadsides. From farther west and south. [P.TRACHYSPERMA Torrey & A. Gray]



POLEMONIUM (Family: Polemoniaceae)


POLEMONIUM CAERULEUM Linnaeus subsp. CAERULEUM - Charity. 2n = 18.


Cemeteries, roadsides, waste places. From Eurasia.


POLEMONIUM REPTANS Linnaeus var. REPTANS - . 2n = 18.


Fields, roadsides, marshes, swamps. From farther west and south.


Polemonium vanbruntiae Britton - . 2n = 18.


Bogs, swamps.



POLYCARPON (Family: Caryophyllaceae)


POLYCARPON TETRAPHYLLUM (Linnaeus) Linnaeus subsp. TETRAPHYLLUM - 2n = 32, 48, 54, 64.


Waste places. From Mediterranean region.



POLYGALA (Family: Polygalaceae)


Polygala ambigua Nuttall - . 2n = ?


Open woodlands, fields, plains, roadsides, often in sandy soil. [P. verticillata Linnaeus var. ambigua (Nuttall) Alph. Wood]


Polygala cruciata Linnaeus var. aquilonia Fernald & B.G. Schubert - . 2n = ?


Meadows, pond shores. marshes, usually in peaty or sandy soil.


Polygala nuttallii Torrey & A. Gray - . 2n = 46.


Dry, sandy fields, open woodlands, railroads, and other dry, sandy open soil.


Polygala paucifolia Willdenow - Fringed Polygala. 2n = 34.


Woodlands, woodland margins, in rich, light soil. [Polygaloides paucifolia (Willdenow) J.R. Abbott]


Polygala polygama Walter - . 2n = 56.


Fields, woodlands, openings, in dry, sandy soil. [P. polygama var. obtusata Chodat]


Polygala sanguinea Linnaeus - . 2n = ?


Fields, meadows, other, moist, open, acid soils.


Polygala senega Linnaeus - Seneca-Snakeroot. 2n = 34.


River terraces, dry woodlands, dry rocky or gravelly areas, usually in calcareous soil.


Polygala verticillata Linnaeus var. verticillata - . 2n = 34.


Fields, open, rocky areas, roadsides, railroads, in sterile, open soil. [P. verticillata var. isocycla Fernald]



POLYGONATUM (Family: Asparagaceae)


Polygonatum biflorum (Walter) Elliott - Great Solomon's-seal. 2n = 20, 40.


Rich or rocky woods, alluvial thickets, riverbanks, hedgerows. [P. biflorum var. commutatum (Schultes (son)) Morong; P. canaliculatum misapplied; P. commutatum (Schultes (son)) A. Dietrich]


POLYGONATUM LATIFOLIUM (Jacquin) Desfontaines - . 2n = 18, 20.


Roadside thickets. From Europe.


Polygonatum pubescens (Willdenow) Pursh - Small Solomon's-seal. 2n = 20, (40).


Dry to rich woods.



POLYGONUM (Family: Polygonaceae)


Polygonum achoreum S.F. Blake - Blue Knotweed. 2n = 40, 60.


Roadsides, waste places.


POLYGONUM ARENARIUM Waldstein & Kitaibel subsp. ARENARIUM - Lesser Red Knotgrass. 2n = 20.


Waste places. From Eurasia.


Polygonum articulatum Linnaeus - Northern Jointweed. 2n = 32.


Dry, sandy wastes, roadsides. [Polygonella articulata (Linnaeus) Meisner]


POLYGONUM AVICULARE Linnaeus subsp. AVICULARE - Common Knotweed. 2n = 40, 60.


Waste places, roadsides. From Eurasia. [P. AVICULARE var. VEGETUM Ledebour]


Polygonum aviculare Linnaeus subsp. buxiforme (Small) Costea & Tardif - American Knotweed. 2n = 60.


Seashores, salt marshes, roadsides, sidewalks, waste places. [P. aviculare var. littorale - misapplied; P. buxiforme Small]


POLYGONUM AVICULARE Linnaeus subsp. DEPRESSUM (Meisner) Arcangeli - Doorweed. 2n = (20), (22), (30), (36), 40, (50), 60.


Roadsides, waste places, fields. From Europe. [P. AVICULARE var. ARENASTRUM (Boreau) Nyman; P. ARENASTRUM Boreau]


POLYGONUM AVICULARE Linnaeus subsp. NEGLECTUM (Besser) Arcangeli - . 2n = (20), (30), 40, (50), 60.


Waste places. From Europe. [P. NEGLECTUM Besser]


POLYGONUM AVICULARE Linnaeus subsp. RURIVAGUM (Jordan ex Boreau) Berher - Cornfield Knotgrass. 2n = 20, 30, 40, 60.


Roadsides, waste places. From Europe. [P. AVICULARE var. ANGUSTISSIMUM Meisner; P. RURIVAGUM Jordan ex Boreau]


POLYGONUM BELLARDII Allioni - . 2n = ?


Waste places. From Europe.


Polygonum douglasii Greene - . 2n = 40.


Dry soil on ledges.


Polygonum erectum Linnaeus - . 2n = ?


Dry, waste places.


Polygonum fowleri B.L. Robinson subsp. fowleri - . 2n = 40, 60.


Seashores. [P. allocarpum S.F. Blake]


Polygonum glaucum Nuttall - Seabeach Knotweed. 2n = 40.


Sea beaches, salty, pond shores, dune hollows.


Polygonum ramosissimum Michaux subsp. ramosissimum - Bushy Knotweed. 2n = 60.


Salt marshes, sea beaches, waste places, roadsides. [P. exsertum Small]


Polygonum ramosissimum Michaux subsp. prolificum (Small) Costea & Tardif - . 2n = 60.


Salt marshes, saline shores. [P. prolificum (Small) B.L. Robinson]


Polygonum tenue Michaux - Pleat-leaved Knotweed. 2n = 20.


Dry, acid, open soil.



POLYMNIA (Family: Asteraceae)


Polymnia canadensis Linnaeus - 2n = 30.


Damp, calcareous woods.



POLYPODIUM (Family: Polypodiaceae)


Polypodium appalachianum Haufler & Windham - Appalachian Polypody. 2n = 74.


Cliffs and rocky slopes.


Polypodium virginianum Linnaeus - Common Polypody. 2n = 74, (111), 148.


On rocks, cliffs, tree bases, rocky (occasionally sandy) slopes, usually in acid soils. [P. vulgare Linnaeus var. virginianum (Linnaeus) Eaton]


Polypodium hybrid

Polypodium X incognitum Cusick - .


[P. appalachianum Haufler & Windham X P. virginianum Linnaeus]



POLYPOGON (Family: Poaceae)


POLYPOGON MONSPELIENSIS (Linnaeus) Desfontaines - Rabbitfoot Grass. 2n = (14), (26), 28, (35), (42).


Wool waste, waste places. From Europe.


POLYPOGON VIRIDIS (Gouan) Breistroffer - Water-bent Grass. 2n = 28.


Waste places. From Eurasia, northern Africa.



POLYSTICHUM (Family: Dryopteridaceae)


Polystichum acrostichoides (Michaux) Schott - Christmas Fern. 2n = 82.


Rocky woods and slopes, occasionally swamps.


Polystichum braunii (Spenner) Fée - Braun's Holly Fern. 2n = 164.


Cool, damp, rocky woods, ravines, and banks in circumneutral soils. [P. braunii var. purshii Fernald; P. braunii subsp. purshii (Fernald) Calder & Roy L. Taylor]


Polystichum hybrid

Polystichum X potteri Barrington
- .


[P. acrostichoides (Michaux) Schott X P. braunii (Spenner) Fée]



PONTEDERIA (Family: Pontederiaceae)


Pontederia cordata Linnaeus - Pickerelweed. 2n = 16.


Shallow water of ponds, lakes and river shores, rooting in mud.



POPULUS (Family: Salicaceae)


POPULUS ALBA Linnaeus - White Poplar. 2n = 38, (40), (45), (57).


Roadsides, waste places, field borders. From Eurasia.


Populus balsamifera Linnaeus - Balsam Poplar. 2n = 38.


Alluvial soils, streambanks, rich, low woods. [P. balsamifera var. subcordata Hylander]


Populus deltoides W. Bartram ex Marshall subsp. deltoides - Cottonwood. 2n = 38.


Streambanks, lake shores, floodplains.


Populus grandidentata Michaux - Bigtooth Aspen. 2n = 38.


Dry woods, recent burns, hillsides.


Populus heterophylla Linnaeus - Swamp Poplar. 2n = ?


Swamps, flooded bottomlands.


POPULUS NIGRA Linnaeus - Lombardy Poplar. 2n = 38, (57).


Roadsides, old house sites. From Eurasia. [P. NIGRA var. ITALICA Münchhausen]


POPULUS TREMULA Linnaeus - European Aspen. 2n = 38, (57).


Waste places. From Eurasia.


Populus tremuloides Michaux - Quaking Aspen. 2n = 38, (57), (76).


Dry, open woods, recent burns and clearings, roadsides. [P. tremuloides var. magnifica Victorin]


Populus hybrids

POPULUS X CANADENSIS Moench (pro species) - .


[P. deltoides W. Bartram ex Marshall X P. NIGRA Linnaeus]


POPULUS X CANESCENS (Aiton) Smith (pro species) - Gray Poplar.


[P. ALBA Linnaeus X P. TREMULA Linnaeus]


Populus X heimburgeri B. Boivin - .


[P. ALBA Linnaeus X P. tremuloides Michaux]


Populus X jackii Sargent - Balm-of-Gilead.


[P. balsamifera Linnaeus X P. deltoides W. Bartram ex Marshall; P. X gileadensis Rouleau]


POPULUS X ROULEAUIANA B. Boivin - .


[P. ALBA Linnaeus X P. grandidentata Michaux]


Populus X smithii B. Boivin - .


[P. grandidentata Michaux X P. tremuloides Michaux]



PORTULACA (Family: Portulacaceae)


PORTULACA GRANDIFLORA Hooker - Moss-rose. 2n = (10), 18, (36).


Dumps, waste places. From South America.


PORTULACA OLERACEA Linnaeus - Common Purslane. 2n = (14), (18), (24), (36), (45), (48), (52), 54.


Waste places, fields. From Europe.



POTAMOGETON (Family: Potamogetonaceae)


Potamogeton alpinus Balbis - Red Pondweed. 2n = 26, 52.


Slow-moving streams, shallow water of ponds and lakes. [P. alpinus var. subellipticus (Fernald) Ogden; P. alpinus var. tenuifolius (Rafinesque) Ogden]


Potamogeton amplifolius Tuckerman - . 2n = 52.


Deep water of lakes and river coves.


Potamogeton berchtoldii Fieber - . 2n = 26.


Quiet, shallow water of ponds and streams. [P. berchtoldii Fieber var. acuminatus Fieber; P. berchtoldii Fieber var. lacunatus (Hagström) Fernald; P. berchtoldii Fieber var. polyphyllus (Morong) Fernald; P. berchtoldii Fieber var. tenuissimus (Mertens & W.D.J. Koch) Fernald; P. pusillus Linnaeus subsp. tenuissimus (Mertens & W.D.J. Koch) R.R. Haynes & Hellquist]


Potamogeton bicupulatus Fernald - . 2n = ?


Acidic, shallow water of rivers and ponds. [P. diversifolius Rafinesque var. trichophyllus Morong; P. capillaceus Poiret (in part)]


Potamogeton confervoides Reichenbach - Alga Pondweed. 2n = ?


Acid sandy or sphagnous ponds, mountain pools and lakes.


POTAMOGETON CRISPUS Linnaeus - Curly Pondweed. 2n = (26), (36), (42), (50), 52, (56), (72), (78).


Shallow, basic or brackish water. From Eurasia. northern Africa.


Potamogeton epihydrus Rafinesque - Ribbonleaf Pondweed. 2n = 26.


Shallow, quiet or moving water. [P. epihydrus var. nuttallii (Chamisso & Schlechtendahl) Fernald;  P. epihydrus var. ramosus (Peck) House]


Potamogeton foliosus Rafinesque subsp. foliosus - Leafy Pondweed. 2n = 14, 28, 30.


Still, basic water of ponds, lakes and streams. [P. foliosus var. macellus Fernald]


Potamogeton friesii Ruprecht - . 2n = 26.


Alkaline, deep water of lakes and ponds.


Potamogeton gemmiparus J.W. Robbins ex Morong - . 2n = ?


Quiet, acidic water of ponds and streams. [P. berchtoldii Fieber subsp. gemmiparus (J.W. Robbins) Les & Tippery; P. pusillus Linnaeus subsp. gemmiparus (J.W. Robbins) R.R. Haynes & Hellquist]


Potamogeton gramineus Linnaeus - . 2n = 52.


Still or flowing water, often in deep water. [P. gramineus var. maximus Morong; P. gramineus var. myriophyllus J.W. Robbins]


Potamogeton hillii Morong - . 2n = ?


Alkaline water of ponds and streams.


Potamogeton illinoensis Morong - . 2n = 104.


Alkaline water of ponds and streams.


Potamogeton natans Linnaeus - Floating Pondweed. 2n = (42), 52, (195).


Ponds and slow streams.


Potamogeton nodosus Poiret - Longleaf Pondweed. 2n = 52.


Streams, lakes, ponds.


Potamogeton oakesianus J.W. Robbins ex A. Gray - Oakes Pondweed. 2n = ?.


Acidic ponds and lakes.


Potamogeton obtusifolius Mertens & W.D.J. Koch - . 2n = 26.


Quiet, usually cold, basic water.


Potamogeton perfoliatus Linnaeus - Redhead-grass. 2n = (14), (26), (48), 52, 78.


Shallow water. [P. perfoliatus var. bupleuroides (Fernald) Farwell]


Potamogeton praelongus Wulfen - White-stem Pondweed. 2n = 52.


Moderately alkaline, still, usually deep water.


Potamogeton pulcher Tuckerman - Spotted Pondweed. 2n = ?.


Acidic, shallow water of ponds and muddy shores.


Potamogeton pusillus Linnaeus - . 2n = 26, (28), (52).


Alkaline water of ponds and streams. [P. pusillus var. minor (Bivona-Bivardi ex Gussone) Fernald & B.G. Schubert]


Potamogeton richardsonii (A. Bennett) Rydberg - Redhead Pondweed. 2n = 26, 52.


Alkaline water of lakes and streams.


Potamogeton robbinsii Oakes - Fern Pondweed. 2n = 52.


Ponds, lakes and slow streams, often in deep water.


Potamogeton spirillus Tuckerman - Northern Snailseed Pondweed. 2n = ?.


Neutral to acidic, quiet water of ponds and streams.


Potamogeton strictifolius A. Bennett - . 2n = 26.


Alkaline water of lakes and slow streams. [P. strictifolius var. rutiloides Fernald]


Potamogeton vaseyi J.W. Robbins ex A. Gray - Vasey's Pondweed. 2n = 28.


Quiet water of ponds and streams of low to moderate alkalinity. [P. lateralis Morong]


Potamogeton zosteriformis Fernald - Flatstem Pondweed. 2n = 26, 52.


Quiet, often alkaline water of ponds and slow streams.



Potamogeton hybrids

Potamogeton X absconditus Z. Kaplan, Fehrer & Hellquist - .


[P. perfoliatus Linnaeus X P. richardsonii (A. Bennett) Rydberg]


Potamogeton X aemulans Z. Kaplan, Hellquist & Fehrer - .


[P. bicupulatus Fernald X P. epihydrus Rafinesque; P. diversifolius misapplied]


Potamogeton amplifolius Tuckerman X P. gramineus Linnaeus - .



Potamogeton amplifolius Tuckerman X P. praelongus Wulfen - .



Potamogeton X argutulus Hagström - .


[P. gramineus Linnaeus X P. nodosus Poiret]


Potamogeton X deminutus Hagström - .


[P. gramineus Linnaeus X P. illinoensis Morong; P. X spathuliformis misapplied]


Potamogeton X faxonii Morong (pro species) - .


[P. illinoensis Morong X P. nodosus Poiret]


Potamogeton gramineus Linnaeus X P. oakesianus J.W. Robbins ex A. Gray - .


[P. X mirabilis Z. Kaplan, Hellquist & Fehrer -- illegitimate name]


Potamogeton X haynesii Hellquist & G.E. Crow - .


[P. strictifolius A. Bennett X P. zosteriformis Fernald; P. longiligulatus misapplied]


Potamogeton illinoensis Morong X P. richardsonii (A. Bennett) Rydberg - .



Potamogeton X luxurians Z. Kaplan - .


[P. amplifolius Tuckerman X P. illinoensis Morong; P. X scoliophyllus misapplied]


Potamogeton X mysticus Morong (pro species) - .


[P. berchtoldii Fieber X P. perfoliatus Linnaeus]


Potamogeton X nitens G. Weber (pro species) - .


[P. gramineus Linnaeus X P. perfoliatus Linnaeus]


Potamogeton X ogdenii Hellquist & R.L. Hilton (pro species) - .


[P. hillii Morong X P. zosteriformis Fernald]


Potamogeton praelongus Wulfen X P. richardsonii (A. Bennett) Rydberg - .



Potamogeton X prussicus Hagström - .


[P. alpinus Balbis X P. perfoliatus Linnaeus]


Potamogeton X subdentatus Hagström - .


[P. illinoensis Morong X P. perfoliatus Linnaeus]


Potamogeton X subsessilis Hagström - .


[P. epihydrus Rafinesque X P. nodosus Poiret]


Potamogeton X versicolor Z. Kaplan, Hellquist & Fehrer - .


[P. epihydrus Rafinesque X P. perfoliatus Linnaeus]



POTENTILLA (Family: Rosaceae)


POTENTILLA ANGLICA Laicharding - Trailing Tormentil. 2n = (28), 56.


Fields. From Europe.


Potentilla anserina Linnaeus subsp. anserina - Common Silverweed. 2n = 28, (35), (42).


Gravelly or sandy shores, swamps, wet fields.


Potentilla anserina Linnaeus subsp. pacifica (Howell) Rousi - Coastal Silverweed. 2n = 28.


Salt marshes, coastal seashores. [P. pacifica Howell]


POTENTILLA ARGENTEA Linnaeus - Silvery Cinquefoil. 2n = 14, 28, (35), 42, (49), 56.


Dry fields, roadsides, dry, open ground. From Eurasia. [P. ARGENTEA var. PSEUDOCALABRA Th. Wolf]


Potentilla canadensis Linnaeus - Dwarf Cinquefoil. 2n = 28.


Dry, sandy fields, roadsides, dry, open ground, often in acidic soil. [P. canadensis var. villosissima Fernald]


POTENTILLA GRACILIS Douglas ex Hooker var. FASTIGIATA (Nuttall) S. Watson - 2n = 91.


Dry meadow. From farther west.


POTENTILLA GRACILIS Douglas ex Hooker var. FLABELLIFORMIS (Lehmann) Nuttall - 2n = 56, 66, 70.


Dry meadow. From farther west.


POTENTILLA INCLINATA Villars - Grey Cinquefoil. 2n = (14), (28), (35), 42, (84).


Dry fields, roadsides, waste places. From Eurasia. [P. CANESCENS Besser]


POTENTILLA INTERMEDIA Linnaeus - Downy Cinquefoil. 2n = 28, (42), 56.


Dry fields, roadsides, waste places. From Eurasia.


Potentilla litoralis Rydberg - 2n = 56.


Dry fields, rocky outcrops, rocky shores, near coast. [P. pectinata Rafinesque – illegitimate name; P. pensylvanica Linnaeus var. litoralis (Rydberg) B. Boivin; P. pensylvanica var. pectinata Lepage]


Potentilla norvegica Linnaeus - Rough Cinquefoil. 2n = (28), (42), 56, 70.


Fields, thickets, roadsides, waste places. [P. norvegica var. labradorica (Lehmann) Fernald]


POTENTILLA PULCHERRIMA Lehmann - 2n = 84.


Meadows. From farther west. [P. GRACILIS Douglas ex Hooker var. PULCHERRIMA (Lehmann) Fernald]


POTENTILLA RECTA Linnaeus - Sulphur Cinquefoil. 2n = (14), 28, 42, (35), (56), (112).


Dry fields, roadsides, waste places. From Eurasia, northern Africa.


POTENTILLA REPTANS Linnaeus - Creeping Cinquefoil. 2n = (20), 28, (42).


Waste places. From Eurasia, northern Africa.


POTENTILLA RIVALIS Nuttall - 2n = 28, 70.


Waste places. From farther west.


Potentilla robbinsiana (Lehmann) Oakes ex Rydberg - 2n = 49.


Alpine rocky slopes and flats.


Potentilla simplex Michaux - Old-field Cinquefoil. 2n = ?


Fields, open woods, thickets, roadsides. [P. simplex var. calvescens Fernald]


POTENTILLA THURINGIACA Bernhardi ex Link - 2n = 42.


Waste places, roadsides. From Eurasia.


POTENTILLA VERNA Linnaeus - 2n = (28), (35), 42, (49), (50), (56), (63), (70), (84).


Grassy roadsides and banks. From Europe. [P. tabernaemontani Ascherson]

POTERIDIUM (Family: Rosaceae)


POTERIDIUM ANNUUM (Nuttall) Spach - Western Burnet. 2n = 14.


Disturbed soil. From farther west. [SANGUISORBA ANNUA (Nuttall) Nuttall]



POTERIUM (Family: Rosaceae)


POTERIUM SANGUISORBA Linnaeus var. POLYGAMUM (Waldstein & Kitaibel) Visiani - Fodder Burnet. 2n = (16), 28, (56).


Old fields, roadsides, quarry ledges, waste places. From Eurasia, northern Africa. [SANGUISORBA MINOR Scopoli subsp. BALEARICA (Nyman) Muñoz Garmendia & C. Navarro; S. MINOR Scopoli subsp. MURICATA (Bonnier & Layens) Briquet]



PRIMULA (Family: Primulaceae)


PRIMULA JAPONICA A. Gray - Japanese Primrose. 2n = 44.


Wet woods. From Japan. [Including the various cultivars to which this name is applied.]


Primula laurentiana Fernald - Bird's-eye Primrose. 2n = 72.


Ledges, meadows, shores, chiefly calcareous.


Primula mistassinica Michaux - Dwarf Canadian Primrose. 2n = 18.


Calcareous cliffs, shores, meadows.


PRIMULA VERIS Linnaeus - Cowslip. 2n = (18), 22, (24).


Shaded slopes, often in calcareous soil. From Europe. [P. OFFICINALIS (Linnaeus) Hill]



PROBOSCIDEA (Family: Martyniaceae)


PROBOSCIDEA LOUISIANICA (Miller) Thellung subsp. LOUISIANICA - . 2n = 30.


Waste places. From farther west.



PROSERPINACA (Family: Haloragaceae)


Proserpinaca intermedia Mackenzie - . 2n = ?


Shallow water and shores of acidic ponds and lakes.


Proserpinaca palustris Linnaeus - . 2n = ?


Shallow water and shores of acidic ponds and lakes. [P. palustris var. crebra Fernald & Griscom]


Proserpinaca pectinata Lamarck - . 2n = ?


Sandy or peaty, acidic ponds, pools, or depressions, swamps.



PRUNELLA (Family: Lamiaceae)


PRUNELLA VULGARIS Linnaeus subsp. VULGARIS - Heal-all. 2n = 28, (32).


Fields, roadsides, waste places. From Eurasia, northwestern Africa.


Prunella vulgaris Linnaeus subsp. lanceolata (W.P.C. Barton) Piper & Beattie - . 2n = 28.


Open, moist woodlands, meadows, streambanks, fields, thickets, roadsides.



PRUNUS (Family: Rosaceae)


Prunus americana Marshall - Wild Plum. 2n = 16.


Fields, Roadsides, thickets, woodland margins. [P. americana var. lanata misapplied; P. americana var. mollis misapplied]


PRUNUS AVIUM (Linnaeus) Linnaeus - Sweet Cherry. 2n = 16, (24), (32).


Roadsides, woods, woodland margins, thickets. From Eurasia.


PRUNUS CERASIFERA Ehrhart - Cherry Plum. 2n = 16, (24), (48).


Roadsides, riverbanks, shores. From Eurasia.


PRUNUS CERASUS Linnaeus - Sour Cherry. 2n = (16), 32.


Roadsides, thickets, woodland margins. From Eurasia.


PRUNUS DOMESTICA Linnaeus subsp. DOMESTICA - Garden Plum. 2n = 16, 32, 48.


Roadsides, thickets, woodland margins, fields. Probably from Eurasia. [P. DOMESTICA subsp. INSITITIA (Linnaeus) C.K. Schneider]


PRUNUS HORTULANA L.H. Bailey - Wild Goose Plum. 2n = 16.


Woodland margins. From farther west.


PRUNUS MAHALEB Linnaeus - Perfumed Cherry. 2n = 16, (24).


Railroads, roadsides, woodland borders, fields. From Eurasia, northern Africa.


Prunus maritima Marshall - Beach Plum. 2n = 16.


Roadsides, dunes, sandy fields, other sandy sites, near seacoast. [P. maritima var. gravesii (Small) G.J. Anderson; P. gravesii Small]


Prunus nigra Aiton - Canada Plum. 2n = ?


Roadsides, thickets, waste places, woodland margins, stream banks.


Prunus pensylvanica Linnaeus (son) - Pin Cherry. 2n = 16.


Dry, open sandy soil, recent burns, dry, open woods and clearings.


PRUNUS PERSICA (Linnaeus) Batsch - Peach. 2n = 16.


Roadsides, thickets. From China.


Prunus pumila Linnaeus var. depressa (Pursh) Bean - Dwarf Sand Cherry. 2n = ?


Sandy, gravelly or rocky river shores, beaches. [P. depressa Pursh]


Prunus pumila Linnaeus var. susquehanae (Willdenow) H. Jaeger - Appalachian Sand Cherry. 2n = ?


Sandy barrens, beaches, clearings, roadsides and fields, dry woods and ledges. [P. pumila var. cuneata (Rafinesque) L.H. Bailey; P. susquehanae Willdenow]


Prunus serotina Ehrhart var. serotina - Black Cherry. 2n = 32.


Thickets, roadsides, wood margins, dry woods, waste places.


PRUNUS SPECIOSA (Koidzumi) Nakai - Japanese Flowering Cherry. 2n = 16.


Mixed woods, roadsides. From Eurasia. [P. SERRULATA misapplied]


PRUNUS SPINOSA Linnaeus - Blackthorn. 2n = 32, (40), (48).


Fields, pond shores. From Eurasia.


Prunus umbellata Elliott - Sloe Plum. 2n = 16.


Roadsides, sandy bottoms, river terraces, fields, rocky copses. [P. alleghaniensis Porter]


Prunus virginiana Linnaeus var. virginiana - Choke Cherry. 2n = ?


Thickets, roadsides, woodland margins.


Prunus hybrid

Prunus serotina Ehrhart var. serotina X P. virginiana Linnaeus var. virginiana - .




PSEUDABUTILON (Family: Malvaceae)


PSEUDABUTILON STUCKERTII R.E. Fries - . 2n = ?


Wool waste. From South America. [WISSADULA CALLIMORPHA (Hochreutiner) Hassler var. FRIESII Hassler]



PSEUDOGNAPHALIUM (Family: Asteraceae)


Pseudognaphalium macounii (Greene) Kartesz - 2n = ?


Dry fields, clearings, woods margins, roadsides. [P. viscosum misapplied; Gnaphalium macounii Greene; G. viscosum misapplied]


Pseudognaphalium micradenium (Weatherby) G.L. Nesom - 2n = ?


Dry, sandy woods, thickets, clearings, roadsides. [Gnaphalium obtusifolium Linnaeus var. micradenium Weatherby]


Pseudognaphalium obtusifolium (Linnaeus) Hilliard & B.L. Burtt - Sweet Everlasting. 2n = 28.


Dry fields, woods margins, dry clearings, roadsides. [Gnaphalium obtusifolium Linnaeus var. obtusifolium; Gnaphalium obtusifolium Linnaeus var. praecox Fernald]



PSEUDOLYCOPODIELLA (Family: Lycopodiaceae)


Pseudolycopodiella caroliniana (Linnaeus) Holub var. caroliniana - Carolina Clubmoss. 2n = 70, 78, 140, 230.


Damp, open sands and peat in acid soils. [Lycopodium carolinianum Linnaeus]



PSEUDOSASA (Family: Poaceae)


PSEUDOSASA JAPONICA (Siebold & Zuccarini ex Steudel) Makino ex Nakai - Arrow Bamboo. 2n = 48.


Woods, stream banks. From eastern Asia. [ARUNDINARIA JAPONICA Siebold & Zuccarini ex Steudel]



PSEUDOTSUGA (Family: Pinaceae)


PSEUDOTSUGA MENZIESII (Mirbel) Franco var. GLAUCA (Beissner) Franco - Rocky Mountain Douglas-fir. 2n = 26.


Woodlands. From farther west.



PTELEA (Family: Rutaceae)


PTELEA TRIFOLIATA Linnaeus subsp. TRIFOLIATA - Common Hoptree. 2n = 36, 42.


Woodland margins, roadsides, waste places. From farther south and west.



PTERIDIUM (Family: Dennstaedtiaceae)


Pteridium aquilinum (Linnaeus) Kuhn subsp. latiusculum (Desvaux) Hultén - Bracken. 2n = 104.


Clearings, pastures, burns, thickets and woods, usually in dry, sterile soils. [P. aquilinum var. latiusculum (Desvaux) L. Underwood ex A. Heller]


Pteridium aquilinum (Linnaeus) Kuhn subsp. pseudocaudatum (Clute) Hultén - Bracken. 2n = ?


Clearings, pastures, burns, thickets and woods, usually in dry, sterile soils. [P. aquilinum var. pseudocaudatum (Clute) A. Heller]



PTEROSPORA (Family: Ericaceae)


Pterospora andromeda Nuttall - Pinedrops. 2n = 16, 48.


Chiefly humus in pine woods, often in basic soil.



PTILIMNIUM (Family: Apiaceae)


Ptilimnium capillaceum (Michaux) Rafinesque - . 2n = 16.


Salt marshes.



PUCCINELLIA (Family: Poaceae)


PUCCINELLIA DISTANS (Jacquin) Parlatore subsp. DISTANS - . 2n = (14), 28, 42.


Roadsides, waste places. From Eurasia, northern Africa.


Puccinellia fasciculata (Torrey) E.P. Bicknell - . 2n = (14), 28, (42).


Salt marshes, brackish shores, sandy seashores.


Puccinellia maritima (Hudson) Parlatore - . 2n = 14, 42, 49, 56, 60, 63, 70, 77.


Salt marshes, brackish shores.


PUCCINELLIA NUTKAENSIS (J. Presl) Fernald & Weatherby - . 2n = (28), (42), 56.


Roadsides, waste places. From Europe. [P. DISTANS (Jacquin) Parlatore subsp. BOREALIS (Holmberg) W.E. Hughes; P. LAURENTIANA Fernald & Weatherby] Note: The voucher for P. LAURENTIANA previously reported for New England from Mt. Desert Island, Maine has been re-identified as P. pumila.


PUCCINELLIA NUTTALLIANA (Schultes) Hitchcock - . 2n = 28, 42, 56.


Moist, alkaline soil. From farther west. [P. AIROIDES (Nuttall) S. Watson & J.M. Coulter]


Puccinellia pumila (Vasey) Hitchcock - . 2n = 42, (56).


Salt marshes, gravelly beaches. [P. paupercula (Holmberg) Fernald & Weatherby var. alaskana misapplied; P. tenella (Lange) Holmberg subsp. alaskana misapplied]



PUERARIA (Family: Fabaceae)


PUERARIA MONTANA (Loureiro) Merrill var. LOBATA (Willdenow) Maesen & S.M. Almeida ex Sanjappa & Predeep - Kudzu. 2n = 22, (24).


Roadsides, waste places. From eastern Asia, southwestern Pacific. [P. LOBATA (Willdenow) Ohwi]



PULMONARIA (Family: Boraginaceae)


PULMONARIA SACCHARATA Miller - Bethlehem Sage. 2n = 22, (25), 26, (27), 28.


Roadsides. Probably from Europe.



PULSATILLA (Family: Ranunculaceae)


PULSATILLA PATENS (Linnaeus) Miller subsp. MULTIFIDA (Pritzel) Zämelis - Pasqueflower. 2n = 16.


Railroads. From farther west. [ANEMONE PATENS Linnaeus var. MULTIFIDA Pritzel]



PYCNANTHEMUM (Family: Lamiaceae)


Pycnanthemum incanum (Linnaeus) Michaux var. incanum - . 2n = 76.


Dry woodlands, thickets.


Pycnanthemum muticum (Michaux) Persoon - . 2n = 40, 80.


Dry woodlands, thickets, clearings.


PYCNANTHEMUM PILOSUM Nuttall - . 2n = 78.


Woodland margins, thickets, dry knolls, sandy fields. From farther west.


Pycnanthemum tenuifolium Schrader - . 2n = 40, (80).


Dry fields, thickets, clearings, roadsides.


Pycnanthemum torreyi Bentham - . 2n = 80.


Dry, rocky woodlands, dry, gravelly banks, meadows.


Pycnanthemum verticillatum (Michaux) Persoon - . 2n = ?


Woodlands, fields, meadows, thickets, clearings, usually in moist soil.


Pycnanthemum virginianum (Linnaeus) B.L. Robinson & Fernald - . 2n = 80.


Fields, shores, meadows, woodlands, thickets, roadsides, usually in moist soil.


Pycnanthemum hybrid

Pycnanthemum X clinopodioides Torrey & A. Gray (pro species) - .


[P. incanum (Linnaeus) Michaux X P. verticillatum (Michaux) Persoon]



PYROLA (Family: Ericaceae)


Pyrola americana Sweet - Round-leaved Pyrola. 2n = 46.


Woods. [P. rotundifolia Linnaeus var. americana (Sweet) Fernald]


Pyrola asarifolia Michaux subsp. asarifolia - Pink Pyrola. 2n = 46.


Rich woods, chiefly calcareous soil. [P. asarifolia var. purpurea (Bunge) Fernald]


Pyrola chlorantha Swartz - Green Pyrola. 2n = (32), 46.


Dry woods. [P. virens Schweigger & Körte var. virens; P. virens var. convoluta (Barton) Fernald]


Pyrola elliptica Nuttall - Shinleaf. 2n = 46.


Dry woods.


Pyrola minor Linnaeus - Snowline Pyrola. 2n = 46.


Cold, damp, coniferous or boreal woods.



PYRUS (Family: Rosaceae)


PYRUS CALLERYANA Decaisne - Callery Pear. 2n = 34.


Shrubby thickets, ditches. From eastern Asia.


PYRUS COMMUNIS Linnaeus - Common Pear. 2n = 34, (51).


Roadsides, fields, thickets, woodland margins. Probably from Eurasia.





Designed by Ray Angelo. Revised Jan. 21, 2017