Ambrosia confertiflora Dc.  
Family: Asteraceae
slimleaf bursage,  more...
[Franseria confertiflora (DC.) Rydb.,  more]
Ambrosia confertiflora image
Max Licher  
Perennials, 20-80(-150+) cm. Stems erect. Leaves mostly alternate; petioles 10-35 mm; blades lanceolate to ovate, 40-85(-150) × 20-35(-55) mm overall, lacini­ately 2-4-pinnately lobed (lobes ± lanceolate); bases cuneate to truncate, ultimate margins entire, abaxial and adaxial faces strigillose to sericeous (often grayish) and gland-dotted. Pistillate heads clustered, proximal to staminates; florets 1(-2). Staminate heads: peduncles 0.5-2 mm; involucres cup-shaped, 1.5-3+ mm diam., strigillose; florets 5-20+. Burs: bodies pyramidal to pyriform, 1-2 mm, strigillose to pilosulous, spines (1-)5-12+, mostly distal, stoutly conic to subulate, 0.5-1 mm, tips uncinate. 2n = 72, 108. Flowering (May-)Sep-Dec. Waste places, disturbed sites; 10-2000 m; Ariz., Calif., Colo., Kans., N.Mex., Okla., Tenn., Tex., Utah; Mexico.
Plant: Perennial, monoecious forb 40-75 cm with deep tap root; herbage with whitish, appressed hairs Leaves: leaves alternate, 6-17 cm long, 2-3 time pinnately divided INFLORESCENCE: primary inflorescence a head, each resembling a flower; staminate heads generally many in ± spikes or racemes, 3-9 mm diam, involucre lobes 5-9, green above; pistillate heads 1(2)-flowered, generally clustered below staminate, generally spiny, bur-like; receptacle chaffy; chaff scales spirally arrayed, fused below, tips generally becoming spiny Flowers: Staminate flowers ± many; corolla yellow or translucent; anthers free; style unbranched; Pistillate flowers 1-5; corolla 0; style branches long Fruit: Fruit: enclosed in a bur 2-5 mm, 1.5-5 mm diam, ovoid, base ± tapered; spines few (sometimes vestigial), scattered, short, cylindric, hooked, pitted at base on upper surface; pappus 0 Misc: Disturbed areas; < 350 m. References: Kearney & Peebles; AZ Flora, McDougall; Seed plants of N.AZ, ASU Specimans.
Ambrosia confertiflora image
Max Licher  
Ambrosia confertiflora image
Max Licher  
Ambrosia confertiflora image
Max Licher  
Ambrosia confertiflora image
Arizona State University Herbarium  
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