3.
Parthenium incanum
Kunth in A. von Humboldt et al., Nov. Gen. Sp. 4(fol.): 204. 1818; 4(qto.): 260. plate 391. 1820.
Mariola
Shrubs,
30—100+ cm.
Leaf blades
oval-elliptic to obovate, 15—25(—40+) × 6—15(—25+) mm, sometimes pinnately (3—)5—7-lobed or round-toothed, ultimate margins entire, faces tomentose (gray to white) and gland-dotted.
Heads
radiate, in glomerules of 3—5+ on branched stalks 1—5(—12+) cm, forming compound, corymbiform arrays.
Peduncles
1—3+ mm.
Phyllaries:
outer 5 oblong, 1.5—2 mm, inner 5 orbiculate, 2—2.5 mm.
Pistillate florets
5; corolla laminae ovate, 1—1.5 mm.
Disc florets
8—20(—30+).
Cypselae
obovoid, 1.5—2 mm; pappus-like enations 2(—3), erect to spreading, ± subulate, 0.5—1 mm.
2
n
= 54.
Flowering (May—)Jul—Nov. Openings in desert scrub, often on limestone soils; 1000—1500 m; Ariz., Nev., N.Mex., Tex., Utah; Mexico.
