Ashy dogweed grows in South Texas Brush Country in Webb and Zapata counties, and historically in Starr County.
Ashy dogweed is an erect perennial with numerous, woolly, 10-30 cm tall stems and minute oil-bearing cells, which give off a strong aroma when the plant is crushed. The leaves are alternate (each leaf attaches at a different point on the stem rather than opposite each other). Leaves are slender or thread-like (8-15 mm long, 0.3-1 mm wide) and sometimes divide into three branches at their tips. Floral stalks are capped with a yellow flower head consisting of a flat disc (composed of 30-70 tiny flowers called disc florets) surrounded by (usually) 12-13, 5-8 mm long, golden yellow petals (ray florets). Just below and cupping the flower head is a white, hairy, upside-down, bell-shaped structure (usually) 5-7 mm tall and 4-8 mm wide. The black fruit is cylindrical to club-shaped with tiny ridges and 3-4 mm long by 0.4 mm wide.
Woolly dogweed (Thymophylla micropoides) occurs in the same vicinity as ashy dogweed. However, woolly dogweed has spreading, shorter (≤10 cm tall) stems, and spoon-shaped leaves. Desert bahia (Bahia absinthifolia) is a much more common species than ashy dogweed, and has a similar leaf and flower color. Because desert bahia has fewer stems, its appearance is less shrubby. Also, desert bahia has opposite lower leaves and leaf edges vary from smooth to notched to lobed.
Ashy dogweed occurs in sandy soils in level or gently rolling grasslands with scattered shrubs.
Life Cycle Events
Flowering occurs from March to May, although is somewhat dependent on rainfall.
Ashy dogweed is easily visible when in flower from March to May, but is recognizable year-round.
- Rare Plants of Texas
- U.S. Fish and Wildlife Service
- Center for Plant Conservation
- Flora of North America
- Poole, J.M. and G.K. Janssen. 1997. Managing and monitoring rare and endangered plants on highway right-of-ways in Texas. Section 6 final report. Austin: Texas Parks & Wildlife Department.