Perityle

Annuals, perennials, subshrubs, or shrubs, 2–45(–75) cm (glabrous or hairy, often gland-dotted). Stems erect to pendent. Leaves mostly cauline; often proximally opposite, distally alternate; petiolate or sessile; blades usually 3-lobed, ultimate margins entire, toothed, or lobed. Heads radiate or discoid, borne singly or in corymbiform arrays. Involucres campanulate, cylindric, funnelform, or hemispheric, 3–15 mm diam. Phyllaries persistent, 5–28 in (1–)2(–3) series (distinct, linear to ovate, equal or subequal, flat or keeled, glabrous or hairy, apices obtuse, acute, or attenuate). Receptacles flat or convex, pitted, epaleate. Ray florets 0, or (1–)3–18, pistillate, fertile; corollas cream, yellow, or white (showy or rudimentary). Disc florets 5–200, bisexual, fertile; corollas cream, yellow, or white, tubes shorter than or nearly equal to cylindric, funnelform, or campanulate throats, lobes 4, ± deltate (acute; stamens 4; style branches flattened, linear, usually tapering to fine, minutely hairy tips). Cypselae (black) flattened to subcylindric, linear to oblanceolate or obovate (margins ± calloused and glabrous, hairy, or ciliate, faces usually hairy, sometimes glabrous); pappi 0, or persistent or falling, of 1–35 bristles plus callous crowns or hyaline scales. x = 17, 19.

Distribution

United States, Mexico, South America.

Discussion

Species 66 (35 in the flora).

Most species of Perityle are rock-dwelling subshrubs exhibiting geographic speciation; most are found in the eroded mountain and basin region of the southwestern United States.

Selected References

None.

Lower Taxa

Perityle sect. Laphamia, Perityle sect. Pappothrix, Perityle sect. Perityle

Key

1	Pappi (disc florets) usually each of 8–35 unequal, antrorsely barbellulate bristles 0.5–3.5 mm (in P. vitreomontana all but 2–3 may be reduced to vestigial nubs); New Mexico, Texas	Perityle sect. Pappothrix
1	Pappi (disc florets) 0, or of 1–2(–6) bristles, sometimes plus callous crowns or scales; Arizona, California, Nevada, New Mexico, Texas, and Utah	> 2
2	Pappi (disc florets) 0, or of 1–2(–3) unequal to subequal, ± barbellate bristles 0.5–4(–6) mm plus hyaline, laciniate scales; margins of cypselae usually densely ciliate	Perityle sect. Perityle
2	Pappi (disc florets) 0, or of 1–2(–6) equal or subequal, antrorsely barbellulate or subplumose bristles 0.5–4.6 mm plus callous crowns or hyaline scales; margins of cypselae usually sparsely short-hairy	Perityle sect. Laphamia