San Pedro matchweed

Gutierrezia gymnospermoides A. Gray, Smithsonian Contr. Knowl. 5(6): 79. 1853; Grindelia gymnospermoides (A. Gray) Ruffin

Plants 30–150 cm, herbage glabrous. Stems usually 1, erect. Leaf blades 40–100 mm, bases narrowly decurrent, margins entire to spinulose-toothed, faces resinous. Heads usually in tight to loose, corymbiform arrays, rarely borne singly. Peduncles: ultimate 1–40 mm, minutely stipitate-glandular. Phyllaries minutely stipitate-glandular. Ray corollas 4–11 mm. Pappi (ray) 0, outer disc 0 or minute crowns, inner nearly 0 or minute crowns, sometimes lacerate or with awnlike scales 0.2–0.8 mm, rarely with ring of persistent, 15–20, antrorsely ciliolate bristles ca. 1.4 mm. 2n = 12.

Flowering (Jul–)Aug–Oct. Meadows, stream bottoms, ditches, grasslands, areas of oak-pine or pine woodlands, usually in habitats at least intermittently wet; 1100–2700 m; Ariz., Tex.; Mexico (Chihuahua, Durango, Jalisco, Sonora, Zacatecas).