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).
Common Name: shrubby thoroughwort
Duration: Perennial
Nativity: Native
Lifeform: Subshrub
General: Perennial subshrubs or shrubs, to 1 m. Stems erect and branched, with puberulent hairs that bend at the tips.
Leaves: Generally opposite, sometimes distally alternate, petioles 2-8 mm, leaves 3-nerved, lanceolate with rounded bases, margins entire or shallowly toothed, acuminate at the tips.
Flowers: Rays white in color, sometimes purple tinged, subtended by large involucres, 4.5-5.5 mm, outermost phyllaries narrowly lanceolate with membranaceous margins.
Fruits: Cypselae sparsely hispidulous.
Ecology: Found on limestone hills and ridges in rocky areas and along canyon walls, talus, slopes, and ledges, in woodlands and along streams, from 2,500-5,500 ft (762-1676 m); flowers September-November.
Notes: This plant looks similar to a Brickellia except for its rays and involucres.
Ethnobotany: Unknown
Etymology: Koanophyllon is a reference to something with the leaves, given that phyllon is related to the Lation word for leaf, while soladginifolium means with leaves like the genus Solidago.
Synonyms: Eupatorium solidagnifolium
Editor: LCrumbacher, 2011
