Neslia paniculata Brassicaceae (4 4 4+2 1) 167

Nicandra physalodes (apple of Peru) Solanaceae ((5) (5) 5 2 hypo) 376 --

Nitella flexilis (a stonewort -- green algae) bears red reproductive structures at leaf nodes

Nuphar advena (southern pond lily) 043 -- N 6/5 N N; petioles terete; stigmatic disk greenish; most lvs held above water

Nuphar microphylla (small pond lily) 042 -- N 6/5 N N; petioles flattened on upper side; red stigmatic disk; lvs 2-4"

Nuphar sp. (pond lily) Nymphaceae --

Nuphar variegata (spatterdock) 042 -- N 6/5 N N; petioles flttend on upper side & nrrwly winged; disk green or grnish; lvs 4-12"

Nyctaginaceae (four o-clock) -- Mirabilis (umbrellawort)

Nymphaea odorata (fragrant white water lily) Nymphaeaceae 043 -- N 4 N N

Nymphaeaceae (water lily) -- Nuphar (yellow water lily); Nymphaea (white water lily)

Nymphoides cordata (little floating heart) Menyanthaceae ((5) 5 5 1or0 sup to half inf) 389 -- along coastal plain

Nymphoides peltata (yellow floating heart) Menyanthaceae ((5) 5 5 1or0 sup to half inf) 389 --

Nyssa aquatica (water tupelo) Cornaceae (staminate: 5-10 5-10 8-15 0; perfect 5-8 5 5-8 1 epi) 306 --

Nyssa sylvatica var biflora (tupelo) Cornaceae -- lf tip rounded

Nyssa sylvatica var sylvatic (tupelo) Cornaceae (staminate: 5-10 5-10 8-15 0; perfect 5-8 5 5-8 1 epi) 306 -- more pointed tip

O

Obolaria virginica (pennywort) Gentianaceae ((4) (2+2) 4 1) 367 -- fls dull wh or prplsh in axils of prpl wedge-shped bracts; lvs OE; rich woods

Ocimum basilicum (basil) Lamiaceae ((5) (5) 2+2 1) 430 -- white fls

Odontites serotina (red bartsia) Scrophulariaceae/Euphrasieae ((5) (5) 2+2 1 stigma 1) 456 -- pink or red in leafy spike; OT lance

Oenothera biennis (common evening primrose) 299 -- A; hairy stem & lvs; sep appendages converging at base

Oenothera fruticosa (southern sundrops) 302 -- eglandular hairs; stamens alternately unequal

Oenothera glazioviana (garden evening primrose) 299 -- A; sep appendages converging at base

Oenothera humifusa (spreading evening primrose) 300 -- B; hairy stem

Oenothera laciniata (cut-leaf evening primrose) 300 -- B; OE cut-leaved

Oenothera parviflora (small-flowered evening primrose) 299 -- A; like O biennis but sep appendages separate from base

Oenothera perennis (small sundrops) 301 -- A; fls smaller; AE lance; stamens alternately unequal

Oenothera sp. (evening primrose) Onagraceae (4 4 8 1 epi) -- A=fruit thickest near the base; B = fr essentially linear

Oenothera tetragona (northern sundrops) 301 -- infl & fr w glnd-tipped hairs; oblng fr; AT lnce to ellip; stamens alternately unequal

Oleaceae (olive) -- Chionanthus (fringe tree), Forsythia, Fraxinus (ash), Ligustrum (privet), Syringa (lilac) -- opp. lvd

Onagraceae (evening primrose) -- Circaea (enchanter's nghtshd), Epilobium (wllw herb), Gaura, Ludwigia (water prmrse), Oenothera (ev primrose)

Onobrychis viciifolia (sainfoin) Fabaceae (5 5 10 1 perf or unisex; peri) 276 --

Onoclea sensibilis (sensitive fern) Onocleaceae 029

Ononis campestris (rest harrow) Fabaceae (5 5 10 1 perf or unisex; peri) 269 --

Onopordum acanthium (Scotch thistle) Asteraceae/Cynareae 585 -- rec flat, fleshy & honeycombed; winged stem; lvs tomentose Onosmodium molle (western false gromwell) Boraginaceae ((5) (5) 5 1 hypo) 401 -- dull white or greenish cor lobes, acuminate; lvs lanceolate+

Onosmodium virginianum (eastern false gromwell) Boraginaceae ((5) (5) 5 1 hypo) 401 -- yellow cor lobes; lvs oblanceolate Ophioglossum vulgatum (adder's tongue) Ophioglossaceae 009

Opuntia humifusa (prickly pear cactus) Cactaceae 086 -- N x N 1 epig

Orchidaceae (orchid) fl plants leafless -- Aplectrum, Arethusa, Corallorhiza, Spiranthes, Tipularia

Orchidaceae (w lvs, lip inflated) -- Calypso, Cypripedium, Epipactis, Goodyera

Orchidaceae (not inflated) -- Arethusa/Calopogon/Cleistes/Epipactis/Habenaira/Isotria/Liparis/Listera/Malaxis/Orchis/Pogonia/Spiranthes/Triphora

Orchis rotundifolia (small round-leaved orchis) Orchidaceae (2+1z 3 1-2 3) 818

Orchis spectabilis (showy orchis) Orchidaceae (2+1z 3 1-2 3) 818 -- magenta fls w a white lip in spike; BE egg, shining

Origanum vulgare (wild marjoram) Lamiaceae ((5) (5) 2+2 1) 413 -- fls pink or purplish; OE long stalked, rnd at base; roadsides & fields Ornithogalum nutans (star of Bethlehem) Liliaceae (3 3 6 3) 787 --

Ornithogallum umbellatum (umbelled star of Bethlehem) Liliaceae (3 3 6 3) 787-- back of wh pets green w/ wh margins; lvs gras-like w/ pale margin

Ornithopus sativus (serradela) Fabaceae (5 5 10 1 perf or unisex; peri) 268 --

Orobanche minor (lesser broomrape) Orobanchaceae ((5) (4) 2+2 1 hypo) 459 --

Orobanche uniflora (one-flowered cancerroot) Orobanchaceae ((5) (5) 2+2 1 hypo) 458 --

Orobanchaceae (broom-rape) -- Conopholis, Epifagus, Orobanche

Orontium aquaticum (golden club) Acoraceae (6 t 6 2-3) 615 --

Oryzopsis asperifolia (rough-leaved rice grass) Poaceae 693 -- single oval fl cluster w bristle soon falling, on short upright branches

Oryzopsis pungens (rice grass) Poaceae 692 --

Oryzopsis racemosa (black-fruited mountain rice grass) Poaceae 693 -- principal lvs cauline

Osmorhiza claytoni (sweet cicely) Apiaceae (5 5 5 2) 347 -- styles shorter than the petals; stem hairy

Osmorhiza chilensis Apiaceae (5 5 5 2) 347 --

Osmorhiza depauperata Apiaceae (5 5 5 2) 347 --

Osmorhiza longistylis (long-styled snakeroot) Apiaceae (5 5 5 2) 347 -- styles longer than the petals; stem nearly smooth or occ. hairy

Osmunda cinnamomea (cinnamon fern) Osmundaceae 010 -- cinnamon tufts

Osmunda claytoniana (interrputed fern) Osmundaceae 010 -- pinnae overlap

Osmunda regalis (royal fern) Osmundaceae 010 --

Ostrya virginiana (eastern hop hornbeam) Betulaceae 082 --

Oxalis stricta (yellow wood sorrel) Oxalidaceae 337 --

Oxalis violacea (violet wood sorrel) Oxalidaceae 338 --

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