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Death Valley sandpaper plant

sandpaper plant, Thurber's sandpaper plant

Habit Plants to 10 dm; branches of current season to 21 cm; hairs on inflorescence-bearing stems soft, ± erect. Shrubs, bushy to moundlike, to 10 dm; branches of current season 12–45 cm.
Leaves

to 20 × 13 mm.

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.

Inflorescences

to 40-flowered.

Flowers

petals to 4.1 mm;

stamens 5–8 mm;

style 4–6 mm.

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.

2n

= 46.

= 46.

Petalonyx thurberi subsp. gilmanii

Petalonyx thurberi

Phenology Flowering May–Sep.
Habitat Sandy washes, sand dunes.
Elevation 400–1000 m. (1300–3300 ft.)
Distribution
from FNA
CA
[BONAP county map]
from FNA
AZ; CA; NV; n Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Subspecies gilmanii is found only in Inyo County.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.)

Key
1. Hairs on inflorescence-bearing stems ± retrorse.
subsp. thurberi
1. Hairs on inflorescence-bearing stems ± erect.
subsp. gilmanii
Source FNA vol. 12, p. 545. FNA vol. 12, p. 545.
Parent taxa Loasaceae > Petalonyx > Petalonyx thurberi Loasaceae > Petalonyx
Sibling taxa
P. thurberi subsp. thurberi
P. linearis, P. nitidus, P. parryi
Subordinate taxa
P. thurberi subsp. gilmanii, P. thurberi subsp. thurberi
Synonyms P. gilmanii
Name authority (Munz) W. S. Davis & H. J. Thompson: Madroño 19: 15. (1967) A. Gray: Pl. Nov. Thurb., 319. (1854)
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