Citation: L., Sp. Pl. 346 (1753).

Derivation: Greek name for a plant probably belonging to this family.

Synonymy: Not Applicable

Common name: Evening-primroses.

Description:
Perennial herbs with a slightly woody base producing usually erect branches ending in an inflorescence, sometimes also annuals; leaves alternate, petiolate to sessile, usually serrate to dentate, rarely pinnately compound.

Inflorescence a spike with few to many sessile flowers each in the axil of a leaf-like bract; floral tube 1.8-11 cm long, glabrous inside, deciduous; sepals 4, usually incompletely separating and bent to one side; petals 4, broadly obovate, truncate, yellow often fading to wine-red, white or pink; stamens 8 in 2 whorls, subequal, with anthers dorsifixed and T-shaped, 6-12 mm long; ovary inferior, with 4 locules, with numerous ovules on an axile placenta; style as long as the stamens, with a terminal stigma of 4 elongate lobes from a basal disk.

Loculicidal capsule opening from the apex; seeds obovoid but often angular, smooth, without hairs.

Distribution:  About 80 species native to North and South America and particularly common in temperate regions of the continent, but some species are now almost cosmopolitan weeds.

Biology: No text

Key to Species:

1. Flowering stems procumbent; leaves pinnately compound, or if pinnatisect then with numerous lobes	O. acaulis 1.
1. Flowering stems erect; leaves toothed, lobed or if pinnatisect at the base then with up to 5 lobes
2. Plants covered with more or less appressed hairs; corolla white or pink	O. speciosa 4.
2. Plants with spreading hairs; corolla yellow turning wine-red
3. Hairs on stems below inflorescence with a broader red base; capsule broadest at the base	O. glazioviana 3.
3. Hairs on stems white; capsule broadened towards the apex
4. Floral tube 8-9 cm long; bracts subtending flowers with a cuneate base; plants silky-hairy	O. affinis 2.
4. Floral tube 1.8-2.4 cm long; bracts subtending flowers with a truncate to auriculate base; plants scarcely hairy	O. stricta 5.

Author: Not yet available