2. Koanophyllon solidaginifolium (A. Gray) R. M. King & H. Robinson, Phytologia. 22: 151. 1971.
Shrubby umbrella thoroughwort
Eupatorium solidaginifolium A. Gray, Smithsonian Contr. Knowl. 3(5): 87. 1852
Perennials or subshrubs (shrubs), 60–100 cm. Stems mostly sparsely puberulent (hairs upcurved or apically bent). Leaves mostly opposite, sometimes subopposite to alternate on distal 1/3 of stems; petioles 2–8(–12) mm; blades lanceolate, mostly 3–8(–11) × 1–3 cm, bases rounded, margins entire or shallowly crenate, apices acuminate, abaxial faces eglandular, adaxial glabrous. Involucres 4.5–5.5 mm. Phyllaries: outermost narrowly lanceolate, glabrous, margins hyaline on proximal 2/3, eciliate. Corollas usually white, sometimes purple-tinged to yellowish, 2.5–3 mm, lobes glandular. Cypselae 1.8–2.8 mm, sparsely hispidulous. 2n = 20.
Flowering (Jun–)Sep–Nov(–Dec). Canyon walls, ledges, slopes, talus, limestone hills and ridges, on and among rocks, in woods along streams; 700–1600 m; Tex.; Mexico (Chihuahua, Coahuila, Durango, Zacatecas).