Isocoma tenuisecta Greene

Some plants approach Isocoma acradenia var. acradenia in leaf and phyllary morphology in southern Arizona, where the ranges of the two taxa overlap.

Herbage minutely hispidulous to hirtellous or sparsely puberulous (at least distal stems), not resinous. Leaf blades oblong-oblanceolate, 20–35 mm, margins pinnatifid (lobes spreading at right angles, linear to filiform). Involucres 4–6.5 × 2–2.8 mm. Phyllary apices with small, sharply delimited, green resinous area, not aristate, often distinctly thickened and approaching resin pockets, usually gland-dotted. Florets 8–12(–15); corollas 4.5–6 mm. Cypsela ribs not forming hornlike extensions.

Haplopappus tenuisectus (Greene) S. F. Blake ex L. D. Benson