Heterotheca

Prairie and Montane Goldenasters and Telegraph Weeds

Heterotheca Cassini includes all the Heterotheca SEM hairsgoldenasters that have leaf hairs consisting of bone-shaped (osteolate) cells with knobbed surfaces.                      

The genus is divided into three sections based on fruit characteristics, presence or absence of ray florets, and growth form. Species of Heterotheca are native to southwestern Canada, much of the U.S. and most of Mexico.

Distribution of Heterotheca in North America

Heterotheca sect. Heterotheca

Heterotheca sect. Heterotheca includes three species with heterocarpic heads (two kinds of fruit; e.g., H. subaxillaris). The two species native to the U.S. are weedy annuals sometimes reaching 2 m in height, but can be short lived perennials in Mexico

Heterotheca sect. Ammodia

Heterotheca sect. Ammodia includes one species H. oregona with four varieties native to gravel bars and arroyos from Washington to Central California. The species has rayless heads.

Heterotheca sect. Phyllotheca

Heterotheca sect. Phyllotheca (Nutt.) Harms (Semple 1996) includes 19 species of mostly herbaceous perennials ranging in height from a few cm (H. jonesii) to more than 1.2 m (H. shevockii). Most species are usually 10-50 cm tall (e.g., H. pumila). Many species are restricted to particular soil types or habitats (e.g., H. brandegei, Baha CA Norte; H. monarchensis, CA; a few species are widely distributed (e.g., H. villosa; nine varieties). Species are defined by different combinations of leaf traits (size, shape, numbers of hairs and glands), head features (size, numbers of florets) and habit (growth form) features. All line drawing illustrations are from Semple (1996) and are © J.C. Semple (1996).

Last update 31 October 2013 by J.C. Semple

© 2013 J.C. Semple, including all photographs unless otherwise indicated