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Annuals, perennials, or subshrubs (delicate or robust, sometimes weedy, in rock crevices or soil). Involucres campanulate to hemispheric, 3–11 × 4–14 mm. Ray florets 0 or (1–)8–18; corollas yellow or white. Disc florets 20–100+; corollas yellow (sometimes pink or purple tinged). Cypselae linear, linear-elliptic, linear-oblong, oblanceolate, oblong, ovate, or subcuneate, usually flattened (outer often 3-angled), margins usually prominently calloused, sometimes thin (not calloused), usually ± densely ciliate; pappi 0 or of 1–2(–3+), unequal to subequal, ± barbellate bristles 0.5–4(–6) mm, sometimes plus crowns of hyaline, laciniate scales. x = 17, 19.
Distribution
United States, Mexico, South America.
Discussion
Species 30 (7 in the flora).
Selected References
Lower Taxa
Key
| 1 | Ray florets 0 (Brewster and Terrell counties, Texas) | Perityle aglossa |
| 1 | Ray florets usually 6–18 (sometimes 0 or 1–6 in P. parryi from w Presidio County, Texas) | > 2 |
| 2 | Ray and disc corollas yellow; Texas | > 3 |
| 2 | Ray corollas white, disc corollas yellow (sometimes purple tinged); Arizona, California, Nevada, New Mexico, Utah | > 4 |
| 3 | Leaves usually cordate to subreniform, margins usually irregularly dentate, laciniate, or ± 3-lobed, seldom more divided (perennials or subshrubs in rock crevices or in soil) | Perityle parryi |
| 3 | Leaves usually ternately lobed or ± cruciform, lobes usually again ternately lobed (perennials in soil) | Perityle vaseyi |
| 4 | Annuals (sometimes persisting) | > 5 |
| 4 | Subshrubs | > 6 |
| 5 | Cypselae (1.5–)2–3 mm, margins thin (not calloused); pappi 0, or of single, antrorsely to retrorsely barbellate bristles 1–3 mm plus crowns of hyaline, laciniate scales | Perityle emoryi |
| 5 | Cypselae 1.5–2 mm, margins prominently calloused; pappi of 2 unequal, antrorsely barbellate bristles 0.8–1.2 mm (the longest) plus crowns of hyaline, laciniate scales | Perityle microglossa |
| 6 | Leaf blades deltate-ovate to ovate-rhombic, margins usually entire or serrate to serrate-crenate, sometimes shallow-lobed; c Arizona | Perityle ciliata |
| 6 | Leaf blades pedately lobed (lobes spatulate or linear) or 2–3-pinnatifid (lobes linear-filiform); s Arizona, New Mexico | Perityle coronopifolia |