Ambrosia trifida

Linnaeus
Sp. Pl. 2: 987. 1753.
Common names: Giant ragweed grande herbe à poux
Illustrated
Synonyms: Ambrosia aptera de Candolle Ambrosia trifida var. integrifolia (Muhlenberg ex Willdenow) Torrey & A. Gray Ambrosia trifida var. texana Scheele
Treatment appears in FNA Volume 21. Treatment on page 14. Mentioned on page 11, 15.

Annuals, 30–150(–400+) cm. Stems erect. Leaves mostly opposite; petioles 10–30(–70+) mm; blades rounded-deltate to ovate or elliptic, 40–150(–250+) × 30–70(–200+) mm, usually some blades palmately 3(–5)-lobed, bases truncate to cuneate (sometimes decurrent onto petioles), margins usually toothed, rarely entire, abaxial and adaxial faces ± scabrellous and gland-dotted. Pistillate heads clustered, proximal to staminates; florets 1. Staminate heads: peduncles 1–3+ mm; involucres ± saucer-shaped, 2–4 mm diam., scabrellous (often with 1–3 black nerves); florets 3–25+. Burs: bodies ± pyramidal, 3–5(–7+) mm, glabrous or glabrate, spines 4–5, ± distal, ± acerose, 0.5–1 mm, tips straight (bases ± decurrent as ribs). 2n = 24, 48.


Phenology: Flowering Jul–Nov.
Habitat: Disturbed sites, waste places, damp soils
Elevation: 0–1600 m

Distribution

V21-13-distribution-map.gif

Alta., B.C., Man., N.B., N.S., Ont., P.E.I., Que., Sask., Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo., Mexico (Chihuahua).

Discussion

The name Ambrosia ×helenae Rouleau applies to hybrids between A. artemisiifolia and A. trifida. Hybrids between A. bidentata and A. trifida have been recorded. Ambrosia trifida may be no longer extant in British Columbia.

Selected References

None.

Lower Taxa

None.

... more about "Ambrosia trifida"
John L. Strother +
Linnaeus +
Giant ragweed +  and grande herbe à poux +
Alta. +, B.C. +, Man. +, N.B. +, N.S. +, Ont. +, P.E.I. +, Que. +, Sask. +, Ala. +, Alaska +, Ariz. +, Ark. +, Calif. +, Colo. +, Conn. +, Del. +, D.C. +, Fla. +, Ga. +, Idaho +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, La. +, Maine +, Md. +, Mass. +, Mich. +, Minn. +, Miss. +, Mo. +, Mont. +, Nebr. +, N.H. +, N.J. +, N.Mex. +, N.Y. +, N.C. +, N.Dak. +, Ohio +, Okla. +, Oreg. +, Pa. +, R.I. +, S.C. +, S.Dak. +, Tenn. +, Tex. +, Utah +, Vt. +, Va. +, Wash. +, W.Va. +, Wis. +, Wyo. +  and Mexico (Chihuahua). +
0–1600 m +
Disturbed sites, waste places, damp soils +
Flowering Jul–Nov. +
Illustrated +
Ambrosia aptera +, Ambrosia trifida var. integrifolia +  and Ambrosia trifida var. texana +
Ambrosia trifida +
Ambrosia +
species +