Ragweed, Slimleaf - Ambrosia confertiflora

(Slimleaf Bursage, Ragweed, Weakleaf Burr Ragweed, (Spanish: Estafiate, Istafiate)

Family: Aster - (Asteraceae) Native


On church wall ad on road after Park Headquarters (N35D32'57.570 X W105D41'16.787)

Flowers first observed: 9/5/17

Plant w/Flowers

The Flowers


" Found on hillsides, slopes, mesas, and sometimes a weed in fields and along roadsides from 1,000-6,500 ft (305-1981 m); flowers March-October.  Distribution: c and s CA, east to s KS, OK, TX; south to c MEX.; also in Australia." (SEINet)


" Perennial herb from a hard, knotty base, with stout, deeply buried, woody taproots; stems often 40-75 cm, erect, and leafy, with white, mostly appressed hairs. Leaves: Mostly alternate, on petioles 1-3.5 cm long; blades green, 6-17 cm long, 2 or 3 times pinnately divided, strigillose to sericeous (often grayish) and gland-dotted. Flowers: Pistillate and staminate flowers in separate heads; all heads discoid; staminate heads pendant in terminal racemes, with a few pistillate heads at the base of each raceme. Pistillate heads with 1 or 2 florets, developing into a single spiny bur at maturity. Staminate heads with cup-shaped involucres, 2-3+ mm in diameter, strigillose; containing 5-20+ disc flowers. Fruits: Burs 2-4 mm with 5-12 small, terete, hooked spines." (SEINet)

Ethnobotanical Uses


"Unknown, but other species in this genus have many uses." (SEINet)

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