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Annual Ragweed

Ambrosia artemisiifolia var. elatior (L.) Descourt.

Comprehensive Description

provided by North American Flora
Ambrosia diversifolia (Piper) Rydberg, sp. nov
Ambrosia artemisiifolia diversifolia Piper, Contr. U. S. Nat. Herb. 11: 551. 1906.
An annual herb, with branched roots; stem about 5 dm. high, strigose-hirsute; lower leaves pinnately divided into oblong or lanceolate divisions, hirsutulous on both sides, somewhat paler beneath; petioles 1-2 cm. long; blades ovate in outline; upper leaves lanceolate or ovate, entire, subsessile, acute; staminate heads numerous, in racemes terminating the branches; involucre 5-6-lobed, 4-5 mm. broad, hispid-strigose; lobes broadly triangular, acute; paleae of the receptacle filiform; corolla puberulent; pistillate heads in few small clusters or solitary in the upper axils; body of the fruit obovoid, about 2.5 mm. long, hirsute-puberulent; beak fully 2 mm. long; spines 4-5, sharp, 0.5-0.8 mm. long.
Type locality: Gravelly banks of Alamota Creek at Alamota, Washington.
Distribution: Washington to Wyoming.
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bibliographic citation
Per Axel, Rydberg. 1922. CARDUALES; AMBROSIACEAE, CARDUACEAE. North American flora. vol 33(1). New York Botanical Garden, New York, NY
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Comprehensive Description

provided by North American Flora
Ambrosia elatior L. Sp. PI. 987. 1753
Ambrosia elata Salisb. Prodr. 175. 1796.
Ambrosia artemisiifolia T. & G. Fl. N. Am. 2: 291, mainly. 1842. Not A. artemisiifolia L. 1753.
Ambrosia artemisiifolia quadricornis Kuntze, Rev. Gen. 305. 1891.
An annual herb, with branched roots; stem 3-10 dm. high, more or less hirsute or hispidulous, branched: leaves bipinnatifid or the upper less divided, hirsutulous-puberulent above, strigose beneath, and often hirsute on the veins; petioles 1-3 cm. long; leaf-blades ovate in outline; rachis winged, 1-3 mm. broad; segments lanceolate, acute, directed forward; staminate heads numerous, or in a predominately pistillate form few or none, in racemes terminating the branches; involucre slightly oblique, about 3 mm. wide, crenate, hirsutulous or hispidulous or in the western form long-hirsute, broadly obconic; paleae of the receptacle filiform ; corolla puberulent; pistillate heads in small clusters in the upper axils; body of the fruit obovoid, 3 mm. long, hispidulous-strigose, or in age almost glabrous, angled and somewhat reticulate; beak subulate, more than 1 mm. long; spines 5-7, subulate, short.
Type locality: Virginia.
Distribution: Nova Scotia to North Carolina, Arkansas, New Mexico, northern California, and Washington; Bermudas; also naturalized in Europe.
license
cc-by-nc-sa-3.0
bibliographic citation
Per Axel, Rydberg. 1922. CARDUALES; AMBROSIACEAE, CARDUACEAE. North American flora. vol 33(1). New York Botanical Garden, New York, NY
original
visit source
partner site
North American Flora