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long leaf sandpaper plant, narrow-leaf sandpaper plant

sandpaper-plant

Habit Subshrubs, bushy, to 16 dm; branches of current season 10–38 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.

Leaves

petiole 0–1 mm;

blade usually elliptic, sometimes falcate, without marked size dimorphism, to 42 × 5 mm, base acute, margins entire, apex rounded to acute.

cauline;

petiole present or absent;

blade ovate, elliptic, lanceolate, or falcate, unlobed, margins dentate, serrate, crenate, or entire.

Inflorescences

60-flowered.

racemes or panicles;

peduncle inconspicuous.

Pedicels

not elongating in fruit.

Flowers

± radially symmetric;

petals spatulate, 5 mm, claws distinct;

stamens exserted distally (not laterally 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.

Fruits

cypselae, ±clavate, straight;

sepals persistent.

Seeds

1, ovoid.

x

= 23.

2n

= 46.

Petalonyx linearis

Petalonyx

Phenology Flowering Mar–Jun.
Habitat Sandy and gravelly canyon and arroyo bottoms, creosote bush scrub.
Elevation 20–1000 m. (100–3300 ft.)
Distribution
from FNA
AZ; CA; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
from USDA
w United States; n Mexico
[BONAP county map]
Discussion

Petalonyx linearis is found in the Sonoran Desert.

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

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.)

Key
1. Leaf blades usually elliptic, sometimes falcate, to 5 mm wide, margins entire; petal claws distinct; stamens exserted distally (not laterally between petal claws).
P. linearis
1. Leaf blades ovate, or if elliptic then to 15–30 mm wide, margins usually serrate, dentate, or crenate, sometimes entire; petal claws postgenitally distally coherent; stamens exserted laterally through slits between petal claws.
→ 2
2. Petioles absent; leaf blades with marked size dimorphism, much larger on main stems than on fertile branches; petals to 6.5 mm.
P. thurberi
2. Petioles 0.5–4 mm; leaf blades without marked size dimorphism; petals 6–15 mm.
→ 3
3. Inflorescences 10–30-flowered; petals 6–11 mm; branches of current season 11–37 cm.
P. nitidus
3. Inflorescences 35–65-flowered; petals 10–15 mm; branches of current season to 13 cm.
P. parryi
Source FNA vol. 12, p. 544. FNA vol. 12, p. 543. Author: Larry Hufford.
Parent taxa Loasaceae > Petalonyx Loasaceae
Sibling taxa
P. nitidus, P. parryi, P. thurberi
Subordinate taxa
P. linearis, P. nitidus, P. parryi, P. thurberi
Name authority Greene: Bull. Calif. Acad. Sci. 1: 188. (1885) A. Gray: Pl. Nov. Thurb., 319. (1854)
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