Argemone polyanthemos

(Fedde) G. B. Ownbey

Mem. Torrey Bot. Club 21: 128. 1958

EndemicSelected by author to be illustratedWeedy
Basionyms: Argemone intermedia var. polyanthemos Fedde in H. G. A. Engler, Pflanzenr. 40[IV,104]: 283. 1909
Treatment appears in FNA Volume 3.
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Illustrator: John Myers
Plants annual or biennial. Stems 4-8(-12) dm, sparingly prickly. Leaf blades: abaxial surface scattered-prickly on main veins, adaxial surface unarmed; proximal lobed 2/3 distance to midrib; distal clasping. Inflorescences: buds ellipsoid-oblong, body 15-22 × 10-15 mm, sparingly prickly; sepal horns terete, 6-10(-15) mm, usually unarmed. Flowers 7-10 cm broad, usually closely subtended by 1-2 foliaceous bracts; petals white, very rarely lavender; stamens 150 or more; filaments lemon yellow; pistil 3-4-carpellate. Capsules narrowly to broadly ellipsoid, 35-50 × 10-17 mm (including stigma and excluding prickles), prickly, surface clearly visible, prickles widely spaced, longest 4-10(-12) mm, interspersed with a few shorter ones. Seeds ca. 2 mm. 2n = 28.

Phenology: Flowering spring–summer; fruiting late spring–summer.
Habitat: Prairies, foothills and mesas
Elevation: 300-2300 m


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Colo., Kans., Mont., Nebr., N.Mex., N.Dak., Okla., S.Dak., Tex., Utah, Wyo.


Argemone polyanthemos is introduced in Utah.



Lower Taxa

No lower taxa listed.