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Aquatic and Wetland Vascular Plants of the Northern Great Plains

Onagraceae - The Evening Primrose Family


Perennial and annual herbs (those included here), often flowering in the first year when perennial. Leaves simple, alternate, opposite or frequently both on the same plant, entire or toothed, sessile or short-petioled, exstipulate. Flowers solitary in the axils of leaves or leaflike bracts, sessile or pedicelled, often arranged in distinct terminal inflorescences (bracteate spikes or racemes), perfect, regular, 4-merous, epigynous, the sepals, petals and stamens arising from the summit of the ovary or from the rim of a short floral tube prolonged beyond the ovary; sepals free; petals free, white, yellow or pinkish to rose-purple; stamens 8 or 4; stigma capitate or often 4-lobed, style 1, ovary 4-celled, often 4-angled, sometimes long and slender to appear like a pedicel or an extension thereof. Fruit a dehiscent, 4-valved capsule or sometimes weakly dehiscent; seeds many, with or without a tuft of hairs (coma).

Lead Characteristic Go To
1 Petals minute or absent, greenish when present; seeds without a coma. Genus Ludwigia
1 Petals white, pinkish or rose-purple; seeds with or without a coma. Lead 2
2 Plants annual; seeds without a coma. Genus Boisduvalia (B. glabella)
2 Plants perennial, often flowering the first year; seeds with a coma. Genus Epilobium


31. Onagraceae, the Evening Primrose Family
1. Boisduvalia Spach
1. Boisduvalia glabella (Nutt.) Walp.
2. Epilobium L. -- Willow herb
1. Epilobium ciliatum Raf.
2. Epilobium coloratum Biehler -- Purple-leaved willow herb
3. Epilobium leptophyllum Raf. -- Narrow-leaved willow herb
3. Ludwigia L. -- Seedbox
1. Ludwigia palustris (L.) Ell. -- Marsh seedbox
2. Ludwigia polycarpa Short & Peter -- Many-seed seedbox


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