QUERCUS (Family: Fagaceae)

Quercus alba Linnaeus - White Oak. 2n = 24.

Dry woods.

Quercus bicolor Willdenow - Swamp White Oak. 2n = 24.

Swamps, stream margins.

QUERCUS CERRIS Linnaeus - Turkey Oak. 2n = 24.

Woodland borders, fields. From Eurasia.

Quercus coccinea Münchhausen - Scarlet Oak. 2n = 24.

Dry woods. [Q. coccinea var. tuberculata Sargent]

Quercus ilicifolia Wangenheim - Scrub Oak. 2n = 24.

Dry, sandy, acidic soil.

QUERCUS IMBRICARIA Michaux - Shingle Oak. 2n = 24.

Roadsides. From farther south and west.

Quercus macrocarpa Michaux - Mossy-cup Oak. 2n = 24.

Rich woods, bottomlands, usually in calcareous soil.

Quercus montana Willdenow - Chestnut Oak. 2n = 24.

Rich woods. [Q. prinus Linnaeus - an ambiguous name]

Quercus muehlenbergii Engelmann - Chinquapin Oak. 2n = 24.

Dry, calcareous slopes.

Quercus palustris Münchhausen - Pin Oak. 2n = 24.

Swampy woods, bottomlands.

Quercus prinoides Willdenow - Dwarf Chinquapin Oak. 2n = 24.

Dry fields, thickets, woodland borders. [Q. prinoides var. rufescens Rehder]

QUERCUS ROBUR Linnaeus - English Oak. 2n = 24.

Roadsides, dry woodland borders. From Europe.

Quercus rubra Linnaeus - Red Oak. 2n = 24.

Dry woods. [Q. rubra var. ambigua Fernald; Q. rubra var. borealis (F. Michaux) Farwell]

Quercus stellata Wangenheim - Post Oak. 2n = 24.

Dry, sterile woods.

Quercus velutina Lamarck - Black Oak. 2n = 24.

Dry woods.

Quercus hybrids

Quercus X bebbiana C.K. Schneider - .

[Q. alba Linnaeus X Q. macrocarpa Michaux]

Quercus X benderi Baenitz - .

[Q. coccinea Münchhausen X Q. rubra Linnaeus]

QUERCUS X BIMUNDORUM E.J. Palmer - .

[Q. alba Linnaeus X Q. ROBUR Linnaeus]

Quercus X faxonii Trelease - .

[Q. alba Linnaeus X Q. prinoides Willdenow]

Quercus X fernaldii Trelease - .

[Q. ilicifolia Wangenheim X Q. rubra Linnaeus]

Quercus X fernowii Trelease - .

[Q. alba Linnaeus X Q. stellata Wangenheim]

Quercus X fontana Laughlin - .

[Q. coccinea Münchhausen X Q. velutina Lamarck]

Quercus X hawkinsii Sudworth - .

[Q. rubra Linnaeus X Q. velutina Lamarck]

Quercus X jackiana C.K. Schneider - .

[Q. alba Linnaeus X Q. bicolor Willdenow]

QUERCUS X LEANA Nuttall (pro species) - .

[Q. IMBRICARIA Michaux X Q. velutina Lamarck]

Quercus X rehderi Trelease - .

[Q. ilicifolia Wangenheim X Q. velutina Lamarck]

Quercus X robbinsii Trelease - .

[Q. coccinea Münchhausen X Q. ilicifolia Wangenheim]

Quercus X saulii C.K. Schneider - .

[Q. alba Linnaeus X Q. montana Willdenow]

Quercus X schuettei Trelease - .

[Q. bicolor Willdenow X Q. macrocarpa Michaux]

Quercus X stelloides E.J. Palmer - .

[Q. prinoides Willdenow X Q. stellata Wangenheim]

Quercus X vaga E.J. Palmer & Steyermark - .

[Q. palustris Münchhausen X Q. velutina Lamarck]

RADIOLA (Family: Linaceae)

RADIOLA LINOIDES Roth - . 2n = 18.

Grassy turf bordering rocky beaches, pastures. From Eurasia, northern and central Africa. [LINUM RADIOLA Linnaeus; MILLEGRANA RADIOLA (Linnaeus) Druce]

RANUNCULUS (Family: Ranunculaceae)

Ranunculus abortivus Linnaeus - Kidneyleaf Crowfoot. 2n = 16.

Damp, rich woods. [R. abortivus var. acrolasius Fernald; R. abortivus var. eucyclus Fernald]

RANUNCULUS ACRIS Linnaeus - Tall Buttercup. 2n = 14, (28), (56).

Moist fields, meadows, roadsides. From Europe. [R. ACRIS var. LATISECTUS Beck]

Ranunculus allegheniensis Britton - Mountain Crowfoot. 2n = 16.

Damp, rocky woods in calcareous soil.

Ranunculus ambigens S. Watson - Water-plantain Spearwort. 2n = ?

Ponds, ditches, brooks.

Ranunculus aquatilis Linnaeus var. diffusus Withering - White Water Crowfoot. 2n = (16), (24), 32, 48.

Ponds, lakes, slow streams. [R. longirostris Godron; R. subrigidus W.B. Drew; R. trichophyllus Chaix var. trichophyllus; R. trichophyllus Chaix var. calvescens W.B. Drew]

RANUNCULUS AURICOMUS Linnaeus - Goldilocks Buttercup. 2n = 16, (24), 32, (40), (48), (56).

Roadsides, fields. From Europe, Greenland.

RANUNCULUS BULBOSUS Linnaeus - Bulbous Buttercup. 2n = (14), 16.

Roadsides, fields, open woods. From Eurasia. [R. BULBOSUS var. DISSECTUS Babey; R. BULBOSUS var. VALDEPUBENS (Jordan) Briquet]

Ranunculus fascicularis Muhlenberg ex Bigelow - Early Buttercup. 2n = 32.

Open hillsides on thin soil, ledges (often calcareous).

Ranunculus flabellaris Rafinesque - Yellow Water Buttercup. 2n = 32.

Shallow water of ponds and quiet streams, drying mud.

Ranunculus flammula Linnaeus var. ovalis (Bigelow) L.D. Benson - Creeping Spearwort. 2n = 32.

Pond and river shores. [R. reptans Linnaeus var. ovalis (Bigelow) Torrey & A. Gray]

Ranunculus flammula Linnaeus var. reptans (Linnaeus) E. Meyer - Creeping Spearwort. 2n = (16), 32, (48).

Pond and river shores. [R. reptans Linnaeus var. reptans]

Ranunculus gmelinii de Candolle - Small Yellow Water Buttercup. 2n = 16, (24), 32, (64).

Muddy pools, brooks, ditches, shores. [R. gmelinii var. hookeri (D. Don) L.D. Benson]

Ranunculus hispidus Michaux var. hispidus - Hispid Buttercup. 2n = 32.

Dry, often rocky, woods. [R. hispidus var. falsus Fernald]

Ranunculus hispidus Michaux var. caricetorum (Greene) T. Duncan - Swamp Buttercup. 2n = 64.

Swampy woods, meadows. [R. septentrionalis Poiret var. caricetorum (Greene) Fernald]

Ranunculus micranthus Nuttall - Rock Buttercup. 2n = 16.

Rich, rocky woods. [R. micranthus var. delitescens (Greene) Fernald]

Ranunculus pensylvanicus Linnaeus (son) - Bristly Crowfoot. 2n = 16.

Meadows, ditches, shores, thickets.

Ranunculus recurvatus Poiret var. recurvatus - Hooked Crowfoot. 2n = 14, 16, 28, 32.

Rich, moist woods, brooksides.

RANUNCULUS REPENS Linnaeus - Creeping Buttercup. 2n = (14), (16), (28), 32.

Wet, open ground, ditches, roadsides. From Eurasia. [R. REPENS var. ERECTUS de Candolle; R. REPENS var. GLABRATUS de Candolle; R. REPENS var. LINEARILOBUS de Candolle; R. REPENS var. PLENIFLORUS Fernald; R. REPENS var. VILLOSUS Lamotte]

RANUNCULUS RHOMBOIDEUS Goldie - Prairie Buttercup. 2n = 16.

Fields. From farther west.

RANUNCULUS SARDOUS Crantz - Hairy Buttercup. 2n = 16, 32, (48).

Fields. From Europe.

Ranunculus sceleratus Linnaeus var. sceleratus - Cursed Crowfoot. 2n = (16), 32, (56), (64).

Marshes, ditches, springy places.

RAPHANUS (Family: Brassicaceae)

RAPHANUS RAPHANISTRUM Linnaeus - Wild Radish. 2n = 18.

Fields, waste places, roadsides, railroads. From Eurasia.

RAPHANUS SATIVUS Linnaeus - Garden Radish. 2n = 18, (28), (36).

Fields, roadsides, waste places. From Eurasia.

RAPISTRUM (Family: Brassicaceae)

RAPISTRUM RUGOSUM (Linnaeus) Allioni - Bastard Cabbage. 2n = 16.

Waste places, roadsides. From Europe. [R. RUGOSUM var. VENOSUM (Persoon) de Candolle]

RATIBIDA (Family: Asteraceae)

RATIBIDA COLUMNIFERA (Nuttall) Wooten & Standley - 2n = (26), (27), 28.

Fields. From farther west.

RATIBIDA PINNATA (Ventenat) Barnhart - Grayhead Prairie-coneflower. 2n = 28.

Waste areas, roadsides. From farther west and south.

RESEDA (Family: Resedaceae)

RESEDA ALBA Linnaeus - White Mignonette. 2n = (20), 40.

Waste places, roadsides. From Eurasia, northern Africa.

RESEDA LUTEA Linnaeus - Yellow Mignonette. 2n = (24), 48.

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

RESEDA LUTEOLA Linnaeus - Dyer’s Rocket. 2n = (24), 26.

Waste places. From Eurasia, northern Africa.

RESEDA ODORATA Linnaeus - Garden Mignonette. 2n = 12, (14).

Waste places. From northern Africa.

REYNOUTRIA (Family: Polygonaceae)

REYNOUTRIA JAPONICA Houttuyn var. JAPONICA - Japanese Knotweed. 2n = 44, 66, 88.

Roadsides, waste places, forest margins. From eastern Asia. [FALLOPIA JAPONICA (Houttuyn) Ronse Decraene; POLYGONUM CUSPIDATUM Siebold & Zuccarini]

REYNOUTRIA SACHALINENSIS Nakai - Giant Knotweed. 2n = (32), 44, (66), (88), (102), (132).

Roadsides, waste places. From eastern Asia. [FALLOPIA SACHALINENSIS (F. Schmidt) Ronse Decraene; POLYGONUM SACHALINENSE F. Schmidt]

Reynoutria hybrid

REYNOUTRIA X BOHEMICA Chrtek & Chrtková - . 2n = 44, 66, 88.

[F. X BOHEMICA (Chrtek & Chrtková) J.P. Bailey; F. JAPONICA (Houttuyn) Ronse Decraene var. JAPONICA X F. SACHALINENSIS (F. Schmidt) Ronse Decraene]

RHAMNUS (Family: Rhamnaceae)

Rhamnus alnifolia L’Héritier - American Alder Buckthorn. 2n = 24.

Bogs, swamps, damp thickets, often with Thuja.

RHAMNUS CATHARTICA Linnaeus - Common Buckthorn. 2n = 24.

Hedgerows, thickets, roadsides, fields, open woodlands. From Eurasia, northwestern Africa.

RHAMNUS DAVURICA Pallas subsp. DAVURICA - . 2n = 24.

Roadsides, woodlands. From eastern Asia. [R. CITRIFOLIA misapplied]

RHEUM (Family: Polygonaceae)

RHEUM RHABARBARUM Linnaeus - Garden Rhubarb. 2n = (22), 44.

Roadsides, old house sites. From Eurasia. [R. RHAPONTICUM misapplied]

RHEXIA (Family: Melastomataceae)

Rhexia mariana Linnaeus var. mariana - . 2n = 22, 44.

Pond shores.

Rhexia virginica Linnaeus - Common Meadow-beauty. 2n = 22, 44.

Peaty meadows, pond shores.

RHINANTHUS (Family: Orobanchaceae)

RHINANTHUS MAJOR Linnaeus - . 2n = 14, 22.

Wet meadows. From Europe. [R. ALECTOROLOPHUS (Scopoli) Pollich]

Rhinanthus minor Linnaeus subsp. minor - . 2n = (14), 22.

Fields, roadsides, thickets, clearings. [R. crista-galli misapplied; R. crista-galli Linnaeus var. fallax W.D.J. Koch ex E.F. Linton]

Rhinanthus minor Linnaeus subsp. groenlandicus (Chabert) Neuman - . 2n = 22.

Turfy subalpine slopes. [R. borealis (Sterneck) Chabert]

RHODIOLA (Family: Crassulaceae)

Rhodiola rosea Linnaeus - Roseroot. 2n = 22.

Sea cliffs, rocky ledges. [Sedum rosea (Linnaeus) Scopoli]

RHODODENDRON (Family: Ericaceae)

RHODODENDRON CALENDULACEUM (Michaux) Torrey - Flame Azalea. 2n = 52.

Roadsides, woods. From farther south and west.

Rhododendron canadense (Linnaeus) Torrey - Rhodora. 2n = 52.

Bogs, swamps, damp thickets, acid barrens, open, rocky summits and slopes.

RHODODENDRON CATAWBIENSE Michaux - Mountain Rosebay. 2n = 26.

Low or wet woods. From farther south.

Rhododendron groenlandicum (Oeder) Kron & Judd - Labrador Tea. 2n = 26.

Peaty soils, especially Sphagnum bogs and swamps. [Ledum groenlandicum Oeder]

RHODODENDRON JAPONICUM (A. Gray) Suringar - Japanese Azalea. 2n = 26.

Swampy woods. From Japan.

Rhododendron lapponicum (Linnaeus) Wahlenberg - Lapland Rosebay. 2n = 26, (52).

Alpine barrens.

Rhododendron maximum Linnaeus - Rosebay. 2n = 26.

Damp woods, swamp margins.

RHODODENDRON MINUS Michaux var. MINUS - Piedmont Rhododendron. 2n = 26.

Woods. From farther south. [R. CAROLINIANUM Rehder]

Rhododendron periclymenoides (Michaux) Shinners - Pinxter-flower. 2n = 26.

Bogs, swamps, wet woods, thickets. [R. nudiflorum misapplied]

Rhododendron prinophyllum (Small) Millais - Roseshell Azalea. 2n = 26.

Damp thickets, banks of streams, wet or dry, rocky woods. [R. roseum misapplied]

RHODODENDRON VASEYI A. Gray - Pinkshell Azalea. 2n = 26.

Swampy woods. From farther south.

Rhododendron viscosum (Linnaeus) Torrey - Swamp Azalea. 2n = 26.

Swampy thickets, shores, damp clearings.

RHODOTYPUS (Family: Rosaceae)

RHODOTYPOS SCANDENS (Thunberg) Makino - Jetbead. 2n = 18.

Waste places, dry, oak-hickory woods, roadsides. From eastern Asia.

RHUS (Family: Anacardiaceae)

Rhus aromatica Aiton var. aromatica - Fragrant Sumac. 2n = ?

Dry ledges, rocky woodlands, often in calcareous soil, thickets as an escape.

Rhus copallinum Linnaeus var. copallinum - Winged Sumac. 2n = ?

Dry woodlands, openings and thickets, roadsides. [R. copallinum var. latifolia Engler]

Rhus glabra Linnaeus - Smooth Sumac. 2n = 30.

Dry fields, roadsides, woodland margins.

Rhus typhina Linnaeus - Staghorn Sumac. 2n = 30.

Open, wooded slopes, woodland margins, fields, roadsides, in dry, rocky or gravelly soil. [R. hirta (Linnaeus) Sudworth - rejected name]

Rhus hybrid

Rhus X pulvinata Greene (pro species) - .

[R. glabra Linnaeus X R. typhina Linnaeus; R. X borealis (Britton) Greene; R. glabra Linnaeus var. borealis Britton]

RHYNCHOSPORA (Family: Cyperaceae)

Rhynchospora alba (Linnaeus) Vahl - . 2n = 26, (42).

Sphagnum bogs.

Rhynchospora capillacea Torrey - . 2n = 26.

Sphagnum bogs, sandy shores, moist, calcareous ledges.

Rhynchospora capitellata (Michaux) Vahl - . 2n = ?

Meadows, shores, low, wet ground.

Rhynchospora fusca (Linnaeus) W.T. Aiton - . 2n = 26, 32.

Bogs, sandy or sphagnous shores.

Rhynchospora inundata (Oakes) Fernald Horned Rush - . 2n = ?

Pond shores, interdunal pools.

Rhynchospora macrostachya Torrey ex A. Gray Horned Rush - . 2n = 18.

Acidic, sandy or sphagnous pond shores.

Rhynchospora nitens (Vahl) A. Gray - . 2n = ?

Acidic, sandy or sphagnous pond shores.  [Psilocarya nitens (Vahl) Alph. Wood]

Rhynchospora scirpoides (Torrey) Grisebach - . 2n = ?

Acidic, sandy or sphagnous pond shores.  [Psilocarya scirpoides Torrey]

Rhynchospora torreyana A. Gray - . 2n = ?

Acidic, sandy or sphagnous pond shores of the coastal plain.

Rhynchospora hybrids

Rhynchospora alba (Linnaeus) Vahl X R. capitellata (Michaux) Vahl

RIBES (Family: Grossulariaceae)

Ribes americanum Miller - Wild Black Currant. 2n = 16.

Rich, wet thickets and slopes.

RIBES AUREUM Pursh var. VILLOSUM de Candolle - Buffalo Currant. 2n = 16.

Old house sites, roadsides. From farther west. [R. ODORATUM H.L. Wendland]

Ribes cynosbati Linnaeus - Prickly Gooseberry. 2n = 16.

Rich, open, usually moist, woods.

Ribes glandulosum Grauer - Skunk Currant. 2n = 16.

Wet woods and clearings.

Ribes hirtellum Michaux - Smooth Gooseberry. 2n = 16.

Rocky woods, swamps. [R. hirtellum var. calcicola (Fernald) Fernald; R. hirtellum var. saxosum (Hooker) Fernald]

Ribes lacustre (Persoon) Poiret - Bristly Black Currant. 2n = 16.

Cold woods and swamps.

RIBES MISSOURIENSE Nuttall - Missouri Gooseberry. 2n = 16.

Roadsides. From farther west.

RIBES NIGRUM Linnaeus - Garden Black Currant. 2n = 16, (24), (32).

Thickets, old house sites. From Eurasia.

Ribes rotundifolium Michaux - Appalachian Gooseberry. 2n = ?

Open rocky places and thickets.

RIBES RUBRUM Linnaeus - Red Garden Currant. 2n = 16.

Old house sites, thickets, riverbanks, open woods, roadsides. From Europe. [R. sativum (Reichenbach) Syme]

Ribes triste Pallas - Wild Red Currant. 2n = 16.

Swampy woods, subalpine ravines.

RIBES UVA-CRISPA Linnaeus - European Gooseberry. 2n = 16.

Fields, roadsides, thickets, woods. From Europe and northern Africa. [R. GROSSULARIA Linnaeus]

RICINUS (Family: Euphorbiaceae)

RICINUS COMMUNIS Linnaeus - Castor-bean. 2n = 20.

Waste places, railroads. Probably from Africa.

ROBINIA (Family: Fabaceae)

ROBINIA HISPIDA Linnaeus var. HISPIDA - Bristly Locust. 2n = 30.

Roadsides, fields, sandy hills, rocky woodland margins, waste places. From farther south.

ROBINIA HISPIDA Linnaeus var. FERTILIS (Ashe) R.T. Clausen - . 2n = 20.

Roadsides. From farther south.

ROBINIA PSEUDOACACIA Linnaeus - Black Locust. 2n = 20, 22.

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

ROBINIA VISCOSA Ventenat var. VISCOSA - Clammy Locust. 2n = 20.

Roadsides, fields, waste places, thickets, often in sandy soil. From farther south.

ROBINIA VISCOSA Ventenat var. HARTWIGII (Koehne) Ashe - . 2n = 20.

Roadsides. From farther south. [R. HARTWIGII Koehne]

Robinia hybrid

ROBINIA X MARGARETTA Ashe (pro species) - .

[R. HISPIDA Linnaeus var. HISPIDA X R. PSEUDOACACIA Linnaeus]

RORIPPA (Family: Brassicaceae)

RORIPPA AMPHIBIA (Linnaeus) Besser - Great Yellow-cress. 2n = 16, 32, (48).

Quiet water, shores, waste places. From Eurasia.

Rorippa aquatica (Eaton) E.J. Palmer & Steyermark - Lake-cress. 2n = 24.

Lakes, quiet streams. [Armoracia aquatica (Eaton) Wiegand; A. lacustris (A. Gray) Al-Shehbaz & V.M. Bates; Neobeckia aquatica (Eaton) Greene]

RORIPPA AUSTRIACA (Cranz) Besser - Austrian Yellow-cress. 2n = 16.

Low fields, muddy shores, ditches. From Europe.

RORIPPA GLOBOSA (Turczaninow ex Fischer & C.A. Meyer) Hayek - Wind Cauliflower. 2n = 16.

Waste places. From eastern Asia.

Rorippa palustris (Linnaeus) Besser subsp. palustris - Lake-cress. 2n = 32.

Shores, damp openings, ditches. [R. palustris subsp. fernaldiana (Butters & Abbe) Jonsell; R. islandica (Oeder ex Murray) Borbás var. fernaldiana Butters & Abbe; R. islandica var. islandica - misapplied]

Rorippa palustris (Linnaeus) Besser subsp. hispida (Desvaux) Jonsell - . 2n = 32.

Shores, damp openings, waste places. [R. islandica (Oeder ex Murray) Borbás var. hispida (Desvaux) Butters & Abbe; R. islandica var. islandica - misapplied]

RORIPPA SYLVESTRIS (Linnaeus) Besser - Creeping Yellow-cress. 2n = (16), 32, 40, 48, (96).

Wet roadsides, meadows, other wet places. From Eurasia.

Rorippa hybrid

RORIPPA X PROSTRATA (J.P. Bergeret) Schinz & Thellung (pro species) - .

[R. AMPHIBIA (Linnaeus) Besser X R. SYLVESTRIS (Linnaeus) Besser]

ROSA (Family: Rosaceae)

Rosa acicularis Lindley subsp. sayi (Schweinitz) W.H. Lewis - 2n = (28), 42, (49), 56.

Railroads, shores, thickets, rocky slopes. [R. acicularis var. bourgeauiana Crépin]

ROSA ARKANSANA Porter - Prairie Rose. 2n = 28, (30).

Railroads. From farther west.

Rosa blanda Aiton - Smooth Rose. 2n = 14, (21), (28).

Shores, riverbanks, meadows, thickets, railroads. [R. blanda var. glabra Crépin; R. johannensis Fernald]

ROSA CANINA Linnaeus - Dog Rose. 2n = (28), 35, (42).

Roadsides, thickets, fields, dry banks.

Rosa carolina Linnaeus subsp. carolina - Pasture Rose. 2n = 28.

Dry pastures, thickets, thin woods, roadsides, other dry, sandy, rocky or open habitats. [R. carolina var. grandiflora (Baker) Rehder; R. carolina var. villosa (Best) Rehder; R. humilis Marshall]

Rosa carolina Linnaeus subsp. subserrulata (Rydberg) W.H. lewis - . 2n = 28.

Ledges.

ROSA CINNAMOMEA Linnaeus - Cinnamon Rose. 2n = 14.

Roadsides, fields, fencerows, clearings. From Eurasia. [R. MAJALIS misapplied]

ROSA GALLICA Linnaeus - French Rose. 2n = 28.

Roadside thickets, waste places. From Eurasia.

ROSA GLAUCA Pourret - 2n = 28.

Roadsides, thickets. From Europe. [R. FERRUGINEA misapplied; R. RUBRIFOLIA Villars]

ROSA LUCIEAE Franchet & Rochebrune ex Crépin - Memorial Rose. 2n = 14.

Thickets, woodland margins. From eastern Asia. [R. WICHURAIANA Crépin]

ROSA MOLLIS Smith - 2n = 28.

Roadsides. From Eurasia.

ROSA MULTIFLORA Thunberg - 2n = 14, (21).

Roadsides, woodland margins, clearings, thickets, waste places. From eastern Asia.

Rosa nitida Willdenow - Northeastern Rose. 2n = 14, (28).

Swamps, bogs, pond shores, wet thickets, in acid soil.

Rosa palustris Marshall - Swamp Rose. 2n = 14. (28), (42).

Swamps, meadows, pastures, wet thickets, shores.

ROSA RUBIGINOSA Linnaeus var. RUBIGINOSA - Sweetbrier. 2n = 35.

Roadsides, fields, thickets, clearings. From Eurasia. [R. EGLANTERIA Linnaeus – ambiguous name]

ROSA RUBIGINOSA Linnaeus var. NEMORALIS (Léman) Thory - Sweetbrier. 2n = (28), 35, (42).

Roadsides, fields, thickets, clearings. From Eurasia, northern Africa. [R. MICRANTHA Borrer]

ROSA RUGOSA Thunberg - Beach Rose. 2n = 14, (21), (28).

Sandy, open soil, often near salt water, roadsides, dunes. From eastern Asia.

ROSA SETIGERA Michaux - Climbing Rose. 2n = 14.

Roadsides, fields, woods, hillsides. From farther west and south. [R. SETIGERA var. TOMENTOSA Torrey & A. Gray]

ROSA SHERARDII Davies - 2n = (28), 35, (42).

Roadsides, pastures. From Europe.

ROSA SPINOSISSIMA Linnaeus - Burnet Rose. 2n = 28.

Roadsides, thickets, fields. From Eurasia. [R. PIMPINELLIFOLIA Linnaeus]

Rosa virginiana Miller - 2n = 28.

Thickets, meadows, swamps, shores, clearings, roadsides. [R. virginiana var. lamprophylla Rehder; R. lucida Ehrhart]

Rosa hybrids

Rosa X atlantica W.H. Lewis - .

[R. carolina Linnaeus X R. palustris Marshall]

Rosa carolina Linnaeus subsp. carolina X R. RUBIGINOSA Linnaeus - .

ROSA X CENTIFOLIA Linnaeus (pro species) - .

[R. GALLICA Linnaeus X ?]

Rosa X churchillii W.H. Lewis - .

[R. blanda Aiton X R. nitida Willdenow]

Rosa X fernaldiorum W.H. Lewis - .

[R. carolina Linnaeus X R. nitida Willdenow]

ROSA X FRANCOFURTANA Münchhausen (pro species) - .

[R. CINNAMOMEA Linnaeus X R. GALLICA Linnaeus]

Rosa X gilmaniana W.H. Lewis - .

[R. blanda Aiton X R. carolina Linnaeus]

Rosa X hainesii W.H. Lewis - .

[R. blanda Aiton X R. virginiana Miller]

Rosa X hodgdonii W.H. Lewis - .

[R. nitida Linnaeus X R. virginiana Miller]

ROSA X MASSIANA W.H. Lewis - .

[R. carolina Linnaeus X R. RUGOSA Thunberg]

Rosa nitida Linnaeus X R. palustris Marshall - .

Rosa X novae-angliae W.H. Lewis - .

[R. carolina Linnaeus subsp. carolina X R. virginiana Miller]

Rosa palustris Marshall X R. virginiana Miller - .

Rosa X per-axeliana W.H. Lewis - .

[R. acicularis Lindley subsp. sayi (Schweinitz) W.H. Lewis X R. aiton Miller]

ROTALA (Family: Lythraceae)

Rotala ramosior (Linnaeus) Koehne - Tooth-cup. 2n = 16, 32.

Sandy or muddy shores of ponds and streams.

RUBUS (Family: Rosaceae)

Due to the significant diversity of taxonomic treatments for this genus over the years, particularly for the large subgenus Eubatus, and the complicated reproductive mechanisms known to occur (hybridization, polyploidy, apomixis), the listing here largely follows the intensive New England study for subgenus Eubatus of Hodgdon and Steele (1966, 1970) . The work of H. Davis, A. Fuller and T. Davis (1967, 1968a, 1968b, 1969a, 1969b, 1970, 1982), H. Davis (1990), Gleason and Cronquist (1991), and the Flora of North America, vol. 9 treatment have been used to help place some names in synonymy.

Rubus allegheniensis Porter - Common Highbush Blackberry. 2n = 14, 21, 28.

Roadsides, fields, clearings, woodland margins, thickets. [R. allegheniensis var. gravesii (Fernald) Fernald; R. allegheniensis var. plausus L.H. Bailey; R. allegheniensis var. populifolius Fernald; R. fernaldianus L.H. Bailey; R. pugnax L.H. Bailey; R. saltuensis L.H. Bailey]

Rubus amicalis Blanchard - 2n = ?

Fields, thickets, waste places, woods, bases of ledges, moist, sphagnous soil. [R. amabilis Blanchard not Focke – illegitimate name; R. elegantulus Blanchard not Forster – illegitimate name]

Rubus arenicola Blanchard - Sand Dewberry. 2n = ?

Dry fields, roadsides, open plains, ledges, especially in dry, open, sandy soil. [R. brainerdii Rydberg; R. curtipes L.H. Bailey; R. janssonii L.H. Bailey; R. obsessus L.H. Bailey; R. pauper L.H. Bailey; R. perpauper L.H. Bailey; R. prosper L.H. Bailey]

Rubus argutus Link - Southern Blackberry. 2n = 14, 21.

Thickets, woodland and bog margins. [R. blakei L.H. Bailey; R. jugosus L.H. Bailey; R. paludivagus Fernald]

RUBUS BIFRONS Vest - Armenian Blackberry. 2n = 28.

Roadsides, waste places. From Eurasia. [R. ARMENIACUS Focke; R. DISCOLOR misapplied]

Rubus canadensis Linnaeus - Smooth Blackberry. 2n = (14), 21, (42).

Moist thickets, clearings in northern hardwood forests, woodland margins, cliff bases.

Rubus chamaemorus Linnaeus - Cloudberry. 2n = 56.

Sphagnum bogs, heaths, often at high elevation.

Rubus cuneifolius Pursh - Sand Blackberry. 2n = 14, 21, 28.

Sandy or rocky, dry open soil on coastal plain. [R. cuneifolius var. spiniceps L.H. Bailey]

Rubus enslenii Trattinnick - 2n = ?

Dry, open, mostly oak-hickory woods, ledges, thickets. [R. baileyanus Britton]

Rubus flagellaris Willdenow - Common Dewberry. 2n = 28.

Dry fields, sandy areas, openings, ledges, thicket borders, roadsides. [R. eflagellaris L.H. Bailey; R. felix L.H. Bailey; ?R. ithacanus L.H. Bailey; R. maniseesensis L.H. Bailey; R. particeps L.H. Bailey; R. villosus misapplied]

Rubus frondosus Bigelow - Yankee Blackberry. 2n = ?

Thickets, fields, roadsides, woodland borders. [R. bellobatus L.H. Bailey; R. insulanus L.H. Bailey; R. multispinus Blanchard; R. recurvans Blanchard; R. rossbergianus Blanchard]

Rubus hispidus Linnaeus - Swamp Dewberry. 2n = 14.

Fields, open woods (specially pine), gravel pits, ditches, swamps, sphagnous soil, Sphagnum bogs, meadows. [R. hispidus var. obovalis (Michaux) Fernald; R. cubitans Blanchard; ?R. novanglicus L.H. Bailey; R. pervarius (L.H. Bailey) L.H. Bailey; R. spiculosus Fernald]

RUBUS IDAEUS Linnaeus subsp. IDAEUS - European Red Raspberry. 2n = 14, (21), (28), (42).

Roadsides, fields, thickets. From Eurasia.

Rubus idaeus Linnaeus subsp. strigosus (Michaux) Focke - Wild Red Raspberry. 2n = 14, 21.

Clearings, fields, roadsides, dry, open woods, damp thickets, woodland borders. [R. idaeus var. canadensis Richardson ex Fernald; R. idaeus var. egglestonii (Blanchard) Fernald; R. idaeus var. heterolasius Fernald]

RUBUS ILLECEBROSUS Focke - Strawberry Raspberry. 2n = 14.

Woods, disturbed sites. From Japan.

Rubus jaysmithii L.H. Bailey - 2n = ?

Dry fields, sandy areas, openings, ledges, thicket borders, roadsides. [R. multifer L.H. Bailey; R. scambens L.H. Bailey; R. tetricus L.H. Bailey]

RUBUS LACINIATUS Willdenow - Cut-leaved Blackberry. 2n = 28.

Roadsides, sandy soil near beaches, railroads, fields, waste places. Probably from Europe.

Rubus occidentalis Linnaeus - Black Raspberry. 2n = 14.

Clearings, thickets, woodland borders, fields.

Rubus odoratus Linnaeus - Purple-flowering Raspberry. 2n = 14.

Woodland borders, open woods, thickets, roadsides, rocky slopes.

RUBUS PARVIFOLIUS Linnaeus - Japanese Raspberry. 2n = 14, 28, (42).

Waste places. From eastern Asia, Australia. [R. TRIPHYLLUS Thunberg]

Rubus pensilvanicus Poiret - 2n = 21, 28.

Thickets, roadsides, swamps, woods, woodland borders, clearings. [R. amnicola Blanchard; R. andrewsianus Blanchard; R. avipes L.H. Bailey; R. barbarus L.H. Bailey; R. conanicutensis L.H. Bailey; R. facetus L.H. Bailey; R. gnarus L.H. Bailey; R. insons L.H. Bailey; ?R. latens L.H. Bailey; R. orarius Blanchard; R. ostryifolius Rydberg not Gandoger – illegitimate name; R. pergratus Blanchard; R. philadelphicus Blanchard]

RUBUS PHOENICOLASIUS Maximowicz - Wineberry. 2n = 14.

Roadsides, thickets, open woods, disturbed, open areas. From eastern Asia.

Rubus pubescens Rafinesque - Dwarf Raspberry. 2n = 14.

Damp woods and slopes, swamps, low thickets, rocky shores, sandy banks. [R. pubescens var. pilosifolius A.F. Hill]

Rubus recurvicaulis Blanchard - Arching Dewberry. 2n = 42.

Fields, railroads, roadsides, other dry or gravelly, open soil. [R. aptatus L.H. Bailey; R. arundelanus Blanchard var. arundelanus; R. arundelanus var. jeckylanus (Blanchard) L.H. Bailey; R. plicatifolius Blanchard; R. positivus L.H. Bailey; R. usus L.H. Bailey]

Rubus repens (Linnaeus) Kuntze - Dewdrop. 2n = 14.

Rich, moist woods, swamps. [R. dalibarda Linnaeus – illegitimate name; Dalibarda repens Linnaeus]

RUBUS RORIBACCUS (L.H. Bailey) Rydberg - Lucretia Dewberry. 2n = ?

Dry woods. From farther west.

Rubus semisetosus Blanchard - Swamp Blackberry. 2n = ?

Swales, swampy thickets, dryish meadows. [R. ascendens Blanchard; R. bigelovianus L.H. Bailey; R. hispidoides L.H. Bailey; R. ortivus (L.H. Bailey) L.H. Bailey; R. perinvisus L.H. Bailey]

Rubus setosus Bigelow - Bristly Blackberry. 2n = ?

Alluvial plains, grassy swamps, swales, damp thickets, waste places. [R. dissimilis L.H. Bailey; R. groutianus Blanchard; R. lawrencei L.H. Bailey; R. notatus L.H. Bailey]

Rubus vermontanus Blanchard - 2n = ?

Clearings, sterile fields, thickets, cliff bases. [R. abbrevians Blanchard; R. junceus Blanchard; R. miscix L.H. Bailey; R. navus L.H. Bailey; R. regionalis (L.H. Bailey) L.H. Bailey; R. tardatus Blanchard]

Rubus hybrids

Rubus allegheniensis Porter X R. amicalis Blanchard - .

Rubus allegheniensis Porter X R. canadensis Linnaeus - .

Rubus allegheniensis Porter X R. flagellaris Willdenow - .

[R. fraternalis L.H. Bailey;]

Rubus allegheniensis Porter X R. frondosus Bigelow - .

Rubus allegheniensis Porter X R. hispidus Linnaeus - .

[R. biformispinus Blanchard; R. invisus (L.H. Bailey) Britton; R. jactus L.H. Bailey; R. laevior (L.H. Bailey) Fernald; R. permixtus Blanchard; R. sanfordii L.H. Bailey]

Rubus allegheniensis Porter X R. pensilvanicus Poiret - .

[R. alumnus L.H. Bailey; R. floricomus Blanchard; R. paulus L.H. Bailey; R. rosa L.H. Bailey]

Rubus allegheniensis Porter X R. recurvicaulis Blanchard - .

Rubus allegheniensis Porter X R. setosus Bigelow - .

[R. aculiferus Fernald; R. frondisentis Blanchard; R. glandicaulis Blanchard; R. montpelierensis Blanchard ex L.H. Bailey; R. sceleratus Brainerd ex Fernald]

Rubus allegheniensis Porter X R. vermontanus Blanchard - .

[R. flavinanus Blanchard; R. ravus L.H. Bailey]

Rubus amicalis Blanchard X R. canadensis Linnaeus - .

Rubus amicalis Blanchard X R. frondosus Bigelow - .

Rubus amicalis Blanchard X R. jaysmithii L.H. Bailey - .

Rubus amicalis Blanchard X R. recurvicaulis Blanchard - .

Rubus amicalis Blanchard X R. setosus Bigelow - .

Rubus amicalis Blanchard X R. vermontanus Blanchard - .

[R. multilicius L.H. Bailey]

Rubus canadensis Linnaeus X R. frondosus Bigelow - .

Rubus canadensis Linnaeus X R. pensilvanicus Poiret - .

Rubus canadensis Linnaeus X R. setosus Bigelow - .

Rubus canadensis Linnaeus X R. vermontanus Blanchard - .

Rubus enslenii Trattinnick X R. frondosus Bigelow - .

Rubus enslenii Trattinnick X R. pensilvanicus Poiret - .

Rubus enslenii Trattinnick X R. recurvicaulis Blanchard - .

Rubus flagellaris Willdenow X R. frondosus Bigelow - .

Rubus flagellaris Willdenow X R. hispidus Linnaeus - .

[R. mainensis L.H. Bailey]

Rubus flagellaris Willdenow X R. recurvicaulis Blanchard - .

Rubus flagellaris Willdenow X R. setosus Bigelow - .

Rubus frondosus Bigelow X R. hispidus Linnaeus - .

Rubus frondosus Bigelow X R. jaysmithii L.H. Bailey - .

Rubus frondosus Bigelow X R. recurvicaulis Blanchard - .

Rubus frondosus Bigelow X R. semisetosus Blanchard - .

Rubus frondosus Bigelow X R. setosus Bigelow - .

Rubus frondosus Bigelow X R. vermontanus Blanchard - .

Rubus hispidus Linnaeus X R. jaysmithii L.H. Bailey - .

Rubus hispidus Linnaeus X R. recurvicaulis Blanchard - .

Rubus hispidus Linnaeus X R. semisetosus Blanchard - .

Rubus hispidus Linnaeus X R. setosus Bigelow - .

[R. adjacens Fernald; R. alter L.H. Bailey; R. blanchardianus (L.H. Bailey) L.H. Bailey; R. harmonicus L.H. Bailey; R. jacens Blanchard; R. pudens L.H. Bailey; R. segnis L.H. Bailey; R. tholiformis Fernald; R. trifrons Blanchard; R. vigoratus L.H. Bailey]

Rubus hispidus Linnaeus X R. setosus Bigelow X R. vermontanus Blanchard - .

Rubus hispidus Linnaeus X R. vermontanus Blanchard - .

Rubus X neglectus Peck (pro species) - .

[R. idaeus Linnaeus subsp. strigosus (Michaux) Focke X R. occidentalis Linnaeus]

Rubus pensilvanicus Poiret X R. recurvicaulis Blanchard - .

Rubus recurvicaulis Blanchard X R. setosus Bigelow - .

[R. arcuans Fernald & H. St. John; R. bicknellii L.H. Bailey; R. multiformis Blanchard; R. provincialis L.H. Bailey]

Rubus recurvicaulis Blanchard X R. vermontanus Blanchard - .

[R. severus Brainerd ex Fernald]

Rubus semisetosus Blanchard X R. setosus Bigelow - .

Rubus setosus Bigelow X R. vermontanus Blanchard - .

[?R. gulosus L.H. Bailey; R. parlinii L.H. Bailey; R. univocus L.H. Bailey]

RUDBECKIA (Family: Asteraceae)

RUDBECKIA FULGIDA Aiton var. SPECIOSA (Wenderoth) Perdue - 2n = 76.

Open swamp, roadsides in moist soil. From farther west and south. [R. SPECIOSA Wenderoth]

Rudbeckia hirta Linnaeus var. hirta - 2n = 38.

Open woods, fields, roadsides.

RUDBECKIA HIRTA Linnaeus var. PULCHERRIMA Farwell - Black-eyed Susan. 2n = 38.

Fields, meadows, clearings, roadsides. From farther west. [R. BICOLOR Nuttall; R. SEROTINA (Nuttall) Sweet var. SEROTINA; R. SEROTINA var. LANCEOLATA (Bischoff) Fernald & B.G. Schubert; R. SEROTINA var. SERICEA (T.V. Moore) Fernald & B.G. Schubert]

Rudbeckia laciniata Linnaeus var. laciniata - 2n = (36), 38, (48), (54), (72), 76, (102).

Swampy thickets, rich, low ground, stream banks, meadows, roadsides. [R. laciniata var. hortensia L.H. Bailey]

RUDBECKIA SUBTOMENTOSA Pursh - Sweet Coneflower. 2n = 38.

Roadsides. From farther west and south.

RUDBECKIA SULLIVANTII C.L. Boynton & Beadle - 2n = 76.

Waste places, roadsides. From farther west.

RUDBECKIA TRILOBA Linnaeus var. TRILOBA - Brown-eyed Susan. 2n = 38, 57.

Field, waste places, roadsides, woods, meadows, stream banks. From farther south and west.

RUMEX (Family: Polygonaceae)

RUMEX ACETOSA Linnaeus - Garden Sorrel. 2n = 14 (pistillate), 15 (staminate).

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

RUMEX ACETOSELLA Linnaeus - Sheep Sorrel. 2n = 14, (15), (21), 28, (32), (35), (40), 42, (56).

Roadsides, fields, waste places, meadows and cemeteries. From Eurasia. [R. ACETOSELLA var. PYRENAICUS (Pourret ex Lapeyrouse) Timbal-Lagrave]

RUMEX ALPINUS Linnaeus - Monk's-rhubarb. 2n = 20.

Roadsides, waste places, fields, meadows. From Eurasia.

RUMEX ALTISSIMUS Alph. Wood - Pale Dock. 2n = 20.

Waste places. From farther west.

Rumex britannica Linnaeus - Water Dock. 2n = 20, 160.

Swamps, ditches, wet meadows, shores. [R. orbiculatus A. Gray]

RUMEX CRISPUS Linnaeus - Yellow Dock. 2n = 60.

Waste places, fields. From Eurasia.

Rumex fueginus Philippi - American Golden Dock. 2n = 40.

Salt marshes, shores, waste places. [R. maritimus Linnaeus var. fueginus (Philippi) Dusén]

Rumex hastatulus Baldwin - Wild Sorrel. 2n = 8 (pistillate), 9 (staminate), 10 (both sexes).

Sandy soil, beaches, waste places.

RUMEX LONGIFOLIUS de Candolle - Northern Dock. 2n = 60, (80).

Fields, meadows, roadsides, waste places. From Eurasia. [R. DOMESTICUS Hartman]

RUMEX MARITIMUS Linnaeus - Golden Dock. 2n = 40.

Ballast, waste places. From Europe.

RUMEX OBTUSIFOLIUS Linnaeus - Bitter Dock. 2n = (20), 40, (60).

Waste places, roadsides, fields, meadows. From Eurasia.

Rumex occidentalis S. Watson - . 2n = 60, 120, 200.

Swamps, shores, swales. [R. aquaticus Linnaeus subsp. fenestratus (Greene) Hultén; R. fenestratus Greene]

Rumex pallidus Bigelow - Seabeach Dock. 2n = 16, 20.

Salt marshes, sea beaches, coastal dunes.

RUMEX PATIENTIA Linnaeus - Patience Dock. 2n = (40), 60, (80).

Waste places, roadsides, fields. From Eurasia.

Rumex persicarioides Linnaeus - . 2n = 40.

Coastal marshes and shores. [R. maritimus Linnaeus var. persicarioides (Linnaeus) R.S. Mitchell)]

RUMEX PSEUDONATRONATUS (Borbás) Murbeck - Finnish Dock. 2n = (20), 40.

Fields, roadsides. From Eurasia.

RUMEX PULCHER Linnaeus - Fiddle Dock. 2n = 20, (40).

Waste places, roadsides. From Eurasia, northern Africa.

RUMEX TRIANGULIVALVIS (Danser) Rechinger (son) - White Willow Dock. 2n = (15), 20.

Railroads, waste places, roadsides, fields. From farther north and west. [R. mexicanus misapplied; R. salicifolius misapplied]

Rumex verticillatus Linnaeus - Swamp Dock. 2n = 60.

Swamps, meadows, marshes.

RUMEX VIOLASCENS Rechinger (son) - Violet Dock. 2n = 20.

Waste places. From farther west.

Rumex hybrids

RUMEX CRISPUS Linnaeus X R. LONGIFOLIUS de Candolle - .

RUMEX CRISPUS Linnaeus X R. OBTUSIFOLIUS Linnaeus - .

RUMEX X DISSIMILIS Rechinger (son) (pro species) - .

[R. LONGIFOLIUS de Candolle X R. OBTUSIFOLIUS Linnaeus]

RUPPIA (Family: Ruppiaceae)

Ruppia maritima Linnaeus - . 2n = (10), 16, 20, (24), 40.

Saline or brackish water. [R. maritima var. longipes Hagström; R. maritima var. obliqua (Schur) Ascherson & Graebner; R. maritima var. rostrata C. Agardh; R. maritima var. subcapitata Fernald & Wiegand]

RUTA (Family: Rutaceae)

RUTA GRAVEOLENS Linnaeus - Common Rue. 2n = 72, (76), (78), (80), (81).

Waste places. From eastern Europe.

Designed by Ray Angelo. Revised March 16, 2023