Boechera williamsii |
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Habit | Perennials; short-lived; sexual; caudex not woody. |
Stems | usually 1 per caudex branch, arising from center of rosette near ground surface, 0.7–2.2 dm, glabrous throughout. |
Basal leaves | blade oblanceolate, 1–2 mm wide, margins entire, ciliate near petiole base, trichomes (simple), to 0.4 mm, surfaces sparsely to densely pubescent, trichomes short-stalked, 4–8-rayed, 0.03–0.1 mm. |
Cauline leaves | 6–11, sometimes concealing stem proximally; blade auricles to 0.5 mm, surfaces of distalmost leaves glabrous. |
Racemes | 5–17-flowered, unbranched. |
Flowers | erect at anthesis; sepals glabrous; petals white, 3–4 × 0.5–0.8 mm, glabrous; pollen ellipsoid. |
Fruiting pedicels | erect, straight, 2–4(–7) mm, glabrous. |
Fruits | erect, usually appressed to rachis, not secund, straight, edges parallel, 2–3.5 cm × 2.2–2.5 mm; valves glabrous; ovules 60–96 per ovary; style 0.05–0.2 mm. |
Seeds | sub-biseriate, 0.7–0.9 × 0.5–0.6 mm, not winged or minutely winged distally. |
Boechera williamsii |
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Phenology | Flowering May–Jun. |
Habitat | Gravelly soil in sagebrush-grassland communities |
Elevation | 2300-2800 m (7500-9200 ft) |
Distribution |
WY |
Discussion | Boechera williamsii is distinguished from all other sexual species of the genus by its combination of relatively short (3–4 mm), white petals, minute, 4–8-rayed trichomes on basal leaves, erect, appressed fruits, and relatively small, wingless seeds. It is known only from Fremont and Sublette counties in west-central Wyoming. The taxon traditionally treated as Arabis (Boechera) williamsii var. saximontana is here recognized as an apomictic species of hybrid origin (see M. D. Windham and I. A. Al-Shehbaz 2007b for detailed comparison). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 411. |
Parent taxa | |
Sibling taxa | |
Synonyms | Arabis williamsii |
Name authority | (Rollins) Dorn: Vasc. Pl. Wyoming ed. 3, 376. (2001) |
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