2. Pectis cylindrica (Fernald) Rydberg in N. L. Britton et al., N. Amer. Fl. 34: 198. 1916.
Three-rayed or Sonoran chinchweed
Pectis prostrata Cavanilles var. cylindrica Fernald, Proc. Amer. Acad. Arts 33: 68. 1897
Annuals, 1–20 cm (across or high); herbage not scented. Stems prostrate to ascending (often mat-forming, densely leafy distally), puberulent (in decurrent lines or throughout) or glabrate. Leaves (bluish green) linear to linear-oblanceolate or narrowly oblong, 10–30 × 1.5–4 mm, margins with 2–5 pairs of setae 1–2 mm, faces glabrous (abaxial densely dotted with scattered, circular oil-glands 0.05–0.2 mm). Heads borne singly or in congested, (leafy) cymiform arrays. Peduncles 1–5 mm. Involucres cylindric. Phyllaries coherent (falling together), oblong to oblong-obovate, 6–10 × 2–3 mm (dotted with scattered, elliptic oil-glands 0.05–0.15 mm). Ray florets 3(–4); corollas 3–4 mm (scarcely surpassing phyllaries). Disc florets (3–)7–14; corollas 2.2–2.6 mm (2-lipped). Cypselae 4–5.5 mm, puberulent (distally glandular-puberulent); pappi of 2 (ray) and 5 (disc) lanceolate scales 1.5–3.5 mm. 2n = 48.
Flowering Jul–Nov. Deserts, oak-juniper woodlands, grasslands, wash channels, mud flats, lawns, roadsides; 700–1500 m; Ariz., N.Mex., Tex.; Mexico (Baja California Sur, Chihuahua, Coahuila, Durango, Nuevo León, Sinaloa, Sonora).
Pectis cylindrica (2n = 48) is similar to P. prostrata (2n = 24); the two occasionally grow together (D. J. Keil 1975b). Some herbaria contain mixed collections of the two. No evidence is available of hybrids between the two.