Heterotheca zionensis Semple is the common species in much of Utah. It was first described from near Zion National Park in southern Utah. The leaves have a high density of short strigose hairs and are also glandular. The leaves can be grayish green to whitish due to the high density of hairs. Most plants are diploid (2n=18), one northern Utah plant was found to be tetraploid (2n=36).
Last revised 30Â April 2025 by J.C. Semple
© 2025 J.C. Semple, including all photographs unless otherwise indicated
1-3. Heterotheca zionensis. 1. Plant on "hotpot", 2n=36, Semple & Chmielewski 8875Â Wasatch Co., Utah. 2. Plant in red sand, 2n=9IISemple & Heard 7859 , type locattion near Zion N.P., Kane Co. Utah. 3-4. Plants along interstate, Semple & B. Semple 10509, near Santa Cruz, New Mexico.
Nesom (2020) treated a plant from Brewster Co., Texas as H. zionensis; I had annotated it as H. canescens in 1993. Nesom (2020) described a possibly closely related species H. utahensis Nesom from NE Utah that has consistently 2-storied stem vestiture, leaf bases rounded to obtuse or truncate at base, and less densely hairy, more glandular leaf surfaces. Nesom included Semple & Chmielewski 8887 from Provo, Utah in his H. utahensis; the collection is tetraploid (2n=36).