Petalonyx nitidus |
Petalonyx |
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shiny-leaf sandpaper plant, smooth sandpaper plant |
sandpaper-plant |
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Habit | Subshrubs or shrubs, bushy to moundlike, to 6 dm; branches of current season 11–37 cm. | Subshrubs or shrubs; trichomes (1) pointed with surfaces ± smooth, notched, or antrorsely barbed, and (2) retrorsely barbed along shaft and at apex. | ||||||||||||
Stems | erect or spreading. |
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Leaves | petiole 1–4 mm; blade ovate, without marked size dimorphism, to 35 × 28 mm, base acute to obtuse, margins serrate to dentate, apex acute. |
cauline; petiole present or absent; blade ovate, elliptic, lanceolate, or falcate, unlobed, margins dentate, serrate, crenate, or entire. |
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Inflorescences | 10–30-flowered. |
racemes or panicles; peduncle inconspicuous. |
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Pedicels | not elongating in fruit. |
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Flowers | slightly bilaterally symmetric through curvature along length of flower; petals spatulate, 6–11 mm, claws postgenitally distally coherent, forming slitted corolla tube; stamens exserted laterally through slits between petal claws. |
hypanthium adnate to ovary proximally, free distally; perianth whorls differentiated; sepals green, connate basally, lanceolate, shorter than petals; petals white, distinct or connate, spatulate or obovate, erect proximally, spreading to divaricate distally (corolla salverform or appearing so), glabrous except hairy abaxially on midribs; nectary distal on ovary; stamens 5, exserted, filaments monomorphic, filiform, longer than anthers; anthers without distal connective extension; staminodes absent [present]; pistil pseudomonomerous, placenta subapical; stigma lingulate, 2-lobed, papillate. |
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Fruits | cypselae, ±clavate, straight; sepals persistent. |
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Seeds | 1, ovoid. |
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x | = 23. |
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2n | = 46. |
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Petalonyx nitidus |
Petalonyx |
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Phenology | Flowering Mar–Aug. | |||||||||||||
Habitat | Sandy, gravelly, or rocky canyon slopes, arroyo bottoms, scrub. | |||||||||||||
Elevation | 400–2200 m. (1300–7200 ft.) | |||||||||||||
Distribution |
AZ; CA; NV; UT
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w United States; n Mexico |
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Discussion | Species 5 (4 in the flora). Petalonyx belongs to subfam. Gronovioideae, which is characterized by relatively small flowers that have five stamens, one ovule, and indehiscent fruits. Petalonyx is most closely related to a clade that consists of Cevallia, Fuertesia Urban, and Gronovia Linnaeus (L. Hufford et al. 2003). Petalonyx crenatus A. Gray ex S. Watson, from Coahuila, Mexico, is the only species of the genus known only from outside the flora area; it can be distinguished from the species treated here by having two anther-bearing stamens and three shorter staminodes, rather than having five anther-bearing stamens. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 544. | FNA vol. 12, p. 543. | ||||||||||||
Parent taxa | Loasaceae > Petalonyx | Loasaceae | ||||||||||||
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Subordinate taxa | ||||||||||||||
Name authority | S. Watson: Amer. Naturalist 7: 300. (1873) | A. Gray: Pl. Nov. Thurb., 319. (1854) | ||||||||||||
Web links |