Isocoma acradenia

(Greene) Greene

Erythea 2: 111. 1894.

Common names: Alkali jimmyweed
Basionym: Bigelowia acradenia Greene Bull. Torrey Bot. Club 10: 126. 1883 (as Bigelovia)
Synonyms: Haplopappus acradenius (Greene) S. F. Blake
Treatment appears in FNA Volume 20. Treatment on page 440.

Herbage usually glabrous, sometimes minutely hispidulous, often stipitate-glandular, often resinous. Leaf blades oblanceolate to narrowly obovate, 20–150 mm, margins entire or toothed or lobed (teeth or lobes apically rounded-obtuse). Involucres 5–8 × 5–7 mm. Phyllary apices yellowish to greenish yellow, sometimes spinulose-aristate, usually not gland-dotted, usually with single, strongly developed, subepidermal resin pocket nearly as wide as bracts, sometimes a central pocket and 2+ smaller, lateral ones (resin pockets sometimes formed from numerous, coalesced, sessile glands). Florets 12–27; corollas 5–7(–8) mm. Cypsela ribs not forming apical horns.



Ariz., Calif., Nev., Utah, nw Mexico.


isocoma acradenia is distinctive in its whitish stems and narrow, whitish-indurate phyllaries with an apical resin pocket (or pockets). the leaves often occur in axillary fascicles

Varieties 3 (3 in the flora).

Selected References



1 Leaves 50–150 mm; florets 20–27; phyllaryapices spinulose-aristate Isocoma acradenia var. bracteosa
1 Leaves 20–50 mm; florets 12–24; phyllary apices usually rounded, not spinulose, sometimes with weakly developed aristae > 2
2 Leaves usually entire, proximal rarely toothed or lobed Isocoma acradenia var. acradenia
2 Leaves all toothed to pinnatifid Isocoma acradenia var. eremophila