Isocoma rusbyi Greene

Herbage glabrous, not resinous. Leaf blades narrowly elliptic-oblong to elliptic-obovate, 20–50 mm, margins entire. Involucres (5.5–)6–9.5 × 5–7.5 mm. Phyllary apices yellowish to greenish yellow, not aristate, sparsely or not at all gland-dotted, without resin pockets. Florets 19–25; corollas 5–6.5 mm. Cypsela ribs slightly surpassing apices, forming hornlike extensions. 2n = 12.