Ambrosia bidentata

Michaux

Fl. Bor.-Amer. 2: 182. 1803

Treatment appears in FNA Volume 21. Treatment on page 15. Mentioned on page 11.
Annuals, 10–30(–100+) cm. Stems erect. Leaves mostly opposite; petioles 0–0.5 mm; blades ± lanceolate to lance-linear, 15–40+ × 3–6(–10+) mm, bases rounded to cordate, margins entire or with (1–)2(–4) basal lobes, abaxial and adaxial faces ± piloso-hispid and gland-dotted. Pistillate heads clustered, proximal to staminates; florets 1. Staminate heads: peduncles 0–0.5 mm; involucres obliquely cup-shaped (lateral lobe longer than others), 2.5–4 mm diam., piloso-hispid; florets 6–8+. Burs: bodies pyramidal, 5–8 mm, piloso-hispid, spines 4(–5), ± distal, ± acerose, 0.5–1 mm, tips straight.

Phenology: Flowering Jul–Oct.
Habitat: Dry, disturbed sites
Elevation: 200–500 m

Distribution

V21-14-distribution-map.gif

Ala., Ark., Conn., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Minn., Miss., Mo., N.C., Ohio, Okla., Tenn., Tex., Va., W.Va.

Discussion

Hybrids between Ambrosia bidentata and A. trifida have been recorded.

References

None.

Lower Taxa

No lower taxa listed.