Hazardia detonsa

(Greene) Greene

Pittonia 1: 29. 1887.

Common names: Island bristleweed
Basionym: Corethrogyne detonsa Greene Bull. Torrey Bot. Club 10: 41. 1883
Synonyms: Haplopappus detonsus (Greene) P. H. Raven
Treatment appears in FNA Volume 20. Treatment on page 449. Mentioned on page 446.

Shrubs, 60–250 cm. Stems lanate-tomentose. Leaves subsessile or subpetiolate; blades obovate, 40–140 × 10–50 mm, subcoriaceous, bases not clasping, margins serrulate to subentire, abaxial faces densely lanate-tomentose, adaxial densely short-tomentose. Heads in thyrsiform to subcorymbiform heads. Involucres campanulate, 10–13 × 10–13 mm. Phyllaries erect, oblong, apices acute, faces densely woolly. Ray florets 6–14, fertile; corollas shorter than involucre, inconspicuous. Disc florets 30–40; corollas 8–10 mm. Cypselae 3–4 mm, canescent. 2n = 10.

Phenology: Flowering Apr–Nov.
Habitat: Open, rocky hillsides, canyon walls, often with Pinus, Quercus, Ceanothus, Rhus, Arctostaphylos
Elevation: 10–300 m


Hazardia detonsa is known from Anacapa, Santa Rosa, and Santa Cruz islands. It is little differentiated from H. cana and clearly its evolutionary sister. In both taxa, the ray and disc florets often change to red-purple with maturity.

Selected References


Lower Taxa