Ambrosia grayi

(A. Nelson) Shinners

Field & Lab. 17: 174. 1949.

Basionym: Gaertneria grayi A. Nelson Bot. Gaz. 34: 35. 1902,
Treatment appears in FNA Volume 21. Treatment on page 17. Mentioned on page 11.

Perennials, 10–30+ cm. Stems erect. Leaves mostly alternate; petioles 10–45+ mm; blades elliptic to ovate, 45–60(–100+) × 30–45(–75+) mm, usually 1–2-pinnately lobed (lobes ± lanceolate), bases cuneate, ultimate margins serrate, abaxial faces densely sericeous or strigillose (silver or grayish), adaxial faces strigillose. Pistillate heads clustered, proximal to staminates; florets (1–)2. Staminate heads: peduncles 1–2 mm; involucres saucer-shaped, 3.5–5+ mm diam., strigillose; florets 8–25(–40+). Burs: bodies ± pyriform to globose, 3–5+ mm, stipitate-glandular, spines 8–12+, scattered, stoutly conic, 0.5–1+ mm, tips straight. 2n = 36.

Phenology: Flowering Aug–Sep.
Habitat: Wet or seasonally wet flats, depressions, alkaline, clay soils, prairies
Elevation: 600–1200 m



Colo., Kans., Nebr., Okla., Tex.


Selected References


Lower Taxa