Ambrosia chamissonis Greene
Family: Asteraceae
Silver Burr-Ragweed
[Ambrosia chamissonis var. bipinnatisecta (Less.) J.T.Howell,  more...]
Ambrosia chamissonis image
Keir Morse  

Perennials, 50-150(-350+) cm. Stems prostrate or decumbent. Leaves mostly alternate; petioles 15-30(-45+) mm; blades rounded-deltate to ovate or obovate, 20-45(-70+) × 10-25(-50+) mm overall, not lobed or 1-2(-3)-pinnately lobed, bases cuneate, ultimate margins entire or toothed, abaxial and adaxial faces strigillose to sericeous. Pistillate heads clustered, proximal to staminates; florets 1. Staminate heads: peduncles 0.5-2 mm; involucres shallowly cup-shaped, 4-6+ mm diam., strigillose; florets 8-25(-50). Burs: bodies fusiform to ± pyriform, 4-7+ mm, ± strigillose to pilosulous, spines 8-16+, scattered, stoutly conic or flattened- to triquetrous-subulate, 0.5-1.5+ mm, tips straight. 2n = 36.

Flowering Apr-Nov. Sandy beaches and strand; 0-10 m; B.C.; Alaska, Calif., Oreg., Wash.; Mexico (Baja California).

Ambrosia chamissonis image
Keir Morse  
Ambrosia chamissonis image
Keir Morse  
Ambrosia chamissonis image
Zoya Akulova  
Ambrosia chamissonis image
Gary A.Monroe  
Ambrosia chamissonis image
Gary A. Monroe  
Ambrosia chamissonis image
Steven Thorsted  
Ambrosia chamissonis image
Steven Thorsted  
Ambrosia chamissonis image
Keir Morse  
Ambrosia chamissonis image
Keir Morse  
Ambrosia chamissonis image
Keir Morse