Petalonyx thurberi |
Petalonyx thurberi subsp. gilmanii |
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sandpaper plant, Thurber's sandpaper plant |
Death Valley sandpaper plant |
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Habit | Shrubs, bushy to moundlike, to 10 dm; branches of current season 12–45 cm. | Plants to 10 dm; branches of current season to 21 cm; hairs on inflorescence-bearing stems soft, ± erect. | ||||
Leaves | petiole absent; blade ovate to elliptic, with marked size dimorphism, to 45 × 15 mm, much larger on main stems than on fertile branches, base acute to rounded, margins usually serrate or crenate, distal often entire, apex acute. |
to 20 × 13 mm. |
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Inflorescences | to 40-flowered. |
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Flowers | conspicuously bilaterally symmetric; petals spatulate, to 6.5 mm, claws postgenitally distally coherent, forming slitted corolla tube; stamens exserted laterally through slits between petal claws. |
petals to 4.1 mm; stamens 5–8 mm; style 4–6 mm. |
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2n | = 46. |
= 46. |
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Petalonyx thurberi |
Petalonyx thurberi subsp. gilmanii |
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Phenology | Flowering May–Sep. | |||||
Habitat | Sandy washes, sand dunes. | |||||
Elevation | 400–1000 m. (1300–3300 ft.) | |||||
Distribution |
AZ; CA; NV; n Mexico
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CA |
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Discussion | Subspecies 2 (2 in the flora). W. S. Davis and H. J. Thompson (1967) called attention to geographical variation in Petalonyx thurberi and distinguished subsp. gilmanii, which is restricted to washes in Inyo County, California, from the widespread subsp. thurberi. Subspecies gilmanii has flowers on the small side of those found among other populations of P. thurberi, although floral attributes do not readily distinguish between the two named subspecies. Davis and Thompson also noted another form that has relatively small leaves on and closely appressed to the inflorescence-bearing stems, although they did not formally distinguish this variant with a name. Morphometric and phylogeographic studies are warranted in P. thurberi to test whether morphological variation is significant, geographically partitioned, and associated with genetically isolated lineages. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Subspecies gilmanii is found only in Inyo County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 545. | FNA vol. 12, p. 545. | ||||
Parent taxa | Loasaceae > Petalonyx | Loasaceae > Petalonyx > Petalonyx thurberi | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. gilmanii | |||||
Name authority | A. Gray: Pl. Nov. Thurb., 319. (1854) | (Munz) W. S. Davis & H. J. Thompson: Madroño 19: 15. (1967) | ||||
Web links |