Perityle
Bot. Voy. Sulphur, 23, plate 15. 1844.
Annuals, perennials, subshrubs, or shrubs, 2–45 (–75) cm (glabrous or hairy, often glanddotted). 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.
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 |