Wireweed

Leaf blades mostly 9–30+ × 1–2(–5+) mm. Peduncles often wiry, ± hirsutulous to pilosulous near heads. Involucres 4–7+ mm. Ray corollas: tubes 1.5–2+ mm, laminae narrowly elliptic, 0.3–1 mm. Disc corollas: tubes 0.2–0.4 mm, throats 1–1.5 mm, lobes 0.1–0.3 mm. Cypselae 4–5 mm; pappi 1–4+ mm or much reduced (rays). 2n = 18.

Rigiopappus leptocladus A. Gray, Proc. Am. Acad. 6: 548. 1865
A slender annual; stem 1-3 dm. high, puberulent; branches 3-10 cm. long, sometimes prolific; leaves 1-3 cm. long, linear, hirsutulous, almost erect; involucre of the principal head 6-7 mm. high and about 1 cm. broad; that of the lateral heads 5 mm. high and 8 mm. broad; bracts hirsutulous, pungent; corollas ochroleucous, 2.5-3 mm. long; achenes 5-6 mm. long, 0.5 mm. thick, hirsutulous; squamellae 4-5 mm. long.
Type locality: Dalles of the Columbia River. Distribution: Washington and Idaho to southern California.

Rigiopappus longiaristatus (A. Gray) Rydberg, sp. nov
Rigiopappus leptocladus longiaristatus A. Gray, Syn. Fl. N. Am. P: 339. 1884.
A slender annual; stem 1-2 dm. high, branched from near the base, puberulent; branches
3-7 cm. long; leaves 1-2 cm. long, linear, hirsutulous, almost erect, those of the branches
about 0.5 mm. long or less; involucre 5 mm. high and about as broad; bracts linear, pungent;
corollas ochroleucous, 2-2.5 mm. long; achenes about 4 mm. long, 0.5 mm. thick, hirsutulous;
squamellae subulate, fully 5 mm. long.
Type locality: Rattlesnake Bar, California. Distribution: California.