20.
Ambrosia confertiflora
de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 526. 1836.
Franseria confertiflora
(de Candolle) Rydberg
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.
2
n
= 72, 108.
Flowering (May—)Sep—Dec. Waste places, disturbed sites; 10—2000 m; Ariz., Calif., Colo., Kans., N.Mex., Okla., Tenn., Tex., Utah; Mexico.
