Northern Prairie Wildlife Research Center
Western Wetland Flora
Field Office Guide to Plant Species
Oenothera flava (A. Nels.) Garrett
- Family: Evening-primrose (Onagraceae)
- Flowering: May-July
- Field Marks: The flowering stem of this plant has no leaves. The woody capsule is winged in the upper half.
- Habitat: Low, dry depressions.
- Habit: Perennial herb with a thick taproot.
- Stems: Only the flower-bearing stem present, upright, up to 1 foot tall, smooth or hairy, the hairs sometimes glandular.
- Leaves: All basal, narrowly oblong to oblanceolate, irregularly toothed or lobed, up to 8 inches long, up to 2 inches wide, smooth or glandular-hairy; leaf stalk slightly winged.
- Flowers: Solitary at the tip of a leafless stem, opening in the evening, up to nearly 2 inches across.
- Sepals: 4, green becoming purplish, more or less free from each other at the tip and
pointing downward, becoming tubular below, the tube up to nearly 3 inches long.
- Petals: 4, pale yellow, free from each other, 1/2-1 inch long.
- Stamens: 6.
- Pistils: Ovary inferior; stigmas 4.
- Fruits: Capsules more or less woody, winged in the upper half, ovoid, 1/2-1 1/2 inches long, with minutely granular, obovoid seeds with a wing-like margin.
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