ARISTOLOCHIA CLEMATITIS Linnaeus - Birthwort. 2n = 14.

Waste places, roadsides, ballast. From Europe.

ARISTOLOCHIA MACROPHYLLA Lamarck - Dutchman's Pipe. 2n = 28.

Woodland borders. From farther south. [ARISTOLOCHIA DURIOR Hill misapplied]

Aristolochia serpentaria Linnaeus - Virginia Snakeroot. 2n = 28, 32.

Rich, often calcareous, woods.

ARISTOLOCHIA TOMENTOSA Sims - Pipevine. 2n = 28.

Thickets. From farther south and west.

Asarum canadense Linnaeus - Wild Ginger. 2n = 26.

Rich woods and shaded, calcareous ledges. [A. canadense var. acuminatum Ashe; A. canadense var. reflexum (E.P. Bicknell) B.L. Robinson]

BERBERIS THUNBERGII de Candolle - Japanese Barberry. 2n = ?

Woods, old fields, pastures, roadsides and other open habitats. From eastern Asia.

BERBERIS VULGARIS Linnaeus - Common Barberry. 2n = ?.

Thickets, pastures, fencerows, roadsides, open woods. From Europe.

Berberis hybrid

BERBERIS X OTTAWENSIS C.K. Schneider - .

[B. THUNBERGII de Candolle X B. VULGARIS Linnaeus]

Caulophyllum giganteum (Farwell) Loconte & W.H. Blackwell - . 2n = 16.

Rich woods.

Caulophyllum thalictroides (Linnaeus) Michaux - Blue Cohosh. 2n = 16.

Rich woods.

PODOPHYLLUM PELTATUM Linnaeus - Mayapple. 2n = 12.

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

ALNUS GLUTINOSA (Linnaeus) Gaertner - Black Alder. 2n = 28.

Damp thickets, stream banks. From Europe.

Alnus incana (Linnaeus) Moench subsp. rugosa (Du Roi) R.T. Clausen - Speckled Alder. 2n = 28.

Swamps, stream margins, lake shores, low grounds. [A. rugosa (Du Roi) Sprengel var. americana (Regel) Fernald]

Alnus serrulata (Aiton) Willdenow - Smooth Alder. 2n = 28.

Swamps, stream margins, lake shores, low grounds.

Alnus viridis (Villars) de Candolle subsp. crispa (Aiton) Turrill - Green Alder. 2n = 28.

Stream banks, swamps. [A. crispa (Aiton) Pursh; A. crispa (Aiton) Pursh var. mollis (Fernald) Fernald]

Alnus hybrids

Alnus X fallacina Callier - .

[Alnus incana Moench subsp. rugosa (Du Roi) R.T. Clausen X A. serrulata (Aiton) Willdenow; A. serrulata (Aiton) Willdenow var. subelliptica Fernald]

ALNUS GLUTINOSA (Linnaeus) Gaertner X A. serrulata (Aiton) Willdenow - .

Betula alleghaniensis Britton - Yellow Birch. 2n = 84.

Rich, often wet, woods, rocky slopes, frequently on boulders. [B. alleghaniensis var. macrolepis (Fernald) Brayshaw; B. lutea F. Michaux; B. lutea F. Michaux var. macrolepis Fernald]

Betula cordifolia Regel - Mountain Paper Birch. 2n = 28, 56.

Moist, rocky slopes, often at upper elevations. [B. papyrifera Marshall var. cordifolia (Regel) Fernald]

Betula glandulosa Michaux - Dwarf Birch. 2n = 28.

Acidic, rocky barrens in subalpine areas. [B. nana misapplied]

Betula lenta Linnaeus - Black Birch. 2n = 28.

Rich woods.

Betula minor (Tuckerman) Fernald - Dwarf White Birch. 2n = 56.

Acidic, rocky barrens in subalpine areas.

Betula nigra Linnaeus - River Birch. 2n = 28.

Riverbanks, flood plains.

Betula papyrifera Marshall - Paper Birch. 2n = 56, 70, 84.

More or less open woods, especially on slopes. [B. papyrifera var. commutata (Regel) Fernald; B. papyrifera var. macrostachya Fernald; B. papyrifera var. pensilis Fernald]

BETULA PENDULA L. Roth - European Weeping Birch. 2n = 28, 56.

Roadsides, thickets, salt marshes. From Eurasia.

Betula populifolia Marshall - Gray Birch. 2n = 28.

Sterile, dry to wet soil, open woods, old fields, waste places.

BETULA PUBESCENS Ehrhart subsp. PUBESCENS - European White Birch. 2n = 56.

Roadsides, thickets. From Europe. [B. ALBA Linnaeus - a rejected name]

Betula pumila Linnaeus - Swamp Birch. 2n = 56.

Bogs, swamps (often calcareous). [B. pumila var. glandulifera Regel; B. pumila var. renifolia Fernald; B. borealis Spach]

Betula hybrids

Betula X caerulea Blanchard - .

[B. cordifolia Regel X B. populifolia Marshall; B. caerulea-grandis Blanchard]

Betula papyrifera Marshall X B. populifolia Marshall - .

Betula X purpusii C. K. Schneider - .

[B. alleghaniensis Britton X B. pumila Linnaeus]

Betula X sandbergii (Britton) Voss - .

[B. papyrifera Marshall X B. pumila Linnaeus]

Carpinus caroliniana Walter subsp. virginiana (Marshall) Furlow - American Hornbeam. 2n = 16.

Stream and swamp borders, rich, moist woods. [C. caroliniana var. virginiana (Marshall) Fernald]

Corylus americana Walter - American Hazelnut. 2n = 22, 28.

Woodland borders, thickets, sandy banks, open woods, roadsides.

Corylus cornuta Marshall subsp. cornuta - Beaked Hazelnut. 2n = 22, 28.

Woodland borders, thickets, sandy banks, open woods, roadsides.

CORYLUS HETEROPHYLLA Fischer ex Trautvetter - Siberian Hazelnut. 2n = 22, 28.

From eastern Asia.

Ostrya virginiana (Miller) K. Koch - American Hop-Hornbeam. 2n = 16.

Rich, dry woods. [O. virginiana var. lasia Fernald]

Brasenia schreberi J.F. Gmelin - Water-shield. 2n = 80.

Ponds, lakes, slow streams.

CABOMBA CAROLINIANA A. Gray - Fanwort. 2n = ca. 78, ca. 104.

Ponds, lakes, slow streams. From farther south and west.

CALYCANTHUS FLORIDUS Linnaeus var. FLORIDUS - Carolina Allspice. 2n = 22, 33.

Along streams, woods. From farther south.

CALYCANTHUS FLORIDUS Linnaeus var. GLAUCUS (Willdenow) Torrey & A. Gray - Carolina Allspice. 2n = 22, 33.

Thickets. From farther south. [C. FERTILIS Walter]

CANNABIS SATIVA Linnaeus - Marijuana. 2n = 20.

Waste places, roadsides. From Asia.

HUMULUS JAPONICUS Siebold & Zuccarini - Japanese Hop. 2n = 20.

Waste places, roadsides. From Asia.

HUMULUS LUPULUS Linnaeus var. LUPULUS - Common Hop. 2n = 20.

Roadsides, waste places, fencerows. From Europe.

Humulus lupulus Linnaeus var. lupuloides E. Small - Common Hop. 2n = 20.

River thickets.

Ceratophyllum demersum Linnaeus - Coontail. 2n = 24, 38, 40, 48.

Quiet water of lakes, ponds and streams.

Ceratophyllum echinatum A. Gray - . 2n = 24.

Quiet water of lakes, ponds and streams.

CERATOPHYLLUM MURICATUM Chamisso subsp. AUSTRALE (Grisebach) Les - . 2n = ?

Ponds. From farther south.

CERCIDIPHYLLUM JAPONICUM Siebold & Zuccarini ex J.J. Hoffmann & J.H. Schultes - Katsura-tree. 2n = 38.

Woods, disturbed areas. From eastern Asia.