Vascular Plants

Includes all flowering plants, conifers, ferns and fern-allies.


Browse by genus:

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z
Genus names beginning with O:
27 genera
60 species
20 subspecies and varieties
Show only taxa with photos
Odontites (1 species)
Oemleria – osoberry (1 species)
Oemleria – Indian plum (1 species)
Oenanthe – oenanthe (1 species)
Oenanthe – water-parsley (1 species)
Oenothera – evening-primrose (8 species)
Oenothera – gaura (8 species)
Oenothera – oenothera (8 species)
Olsynium – purple-eyed grass (1 species)
Olsynium – grass-widow (1 species)
Onobrychis – sainfoin (1 species)
Ononis (1 species)
Onopordum – cotton-thistle (1 species)
Ophioglossum – adder's-tongue (1 species)
Oplopanax (1 species)
Opuntia – pricklypear cactus (2 species)
Oreopteris – mountain fern (1 species)
Oreostemma – aster (1 species)
Oreostemma – mountaincrown (1 species)
Origanum – wild marjoram (1 species)
Ornithogalum – ornithogale (2 species)
Ornithogalum – star-of-Bethlehem (2 species)
Orobanche – broomrape (1 species)
Orobanche – cancer-root (1 species)
Orthilia – one-sided wintergreen (1 species)
Orthocarpus – owl-clover (5 species)
Oryzopsis – ricegrass (1 species)
Osmorhiza – sweet-cicely (4 species)
Osmorhiza – sweet-root (4 species)
Osmunda (1 species)
Oxalis – lady's-sorrel (7 species)
Oxalis – oxalis (7 species)
Oxalis – wood-sorrel (7 species)
Oxybasis – goosefoot (4 species)
Oxyria – mountain sorrel (1 species)
Oxytheca – oxytheca (1 species)
Oxytheca – puncturebract (1 species)
Oxytropis – crazyweed (3 species)
Oxytropis – locoweed (3 species)
Oxytropis – oxytrope (3 species)
Ozomelis – mitrewort (3 species)
Ozomelis – ozomelis (3 species)