Athysanus pusillus

(Hooker) Greene

Bull. Calif. Acad. Sci. 1: 72. 1885

Basionyms: Thysanocarpus pusillus Hooker Icon. Pl. 1: plate 42. 1837
Synonyms: Athysanus pusillus var. glabrior S. Watson Thysanocarpus oblongifolius unknown
Treatment appears in FNA Volume 7. Treatment on page 267. Mentioned on page 268.
Click plate for higher resolution version.
Plants sparsely to densely pubescent proximally, sometimes glabrous distally. Stems (0.2–)0.5–3(–5) dm. Basal leaves: petiole 0.1–0.5 cm; blade oblanceolate, obovate, or oblong, 0.3–1.5(–2) cm × (1–)2–6(–8) mm, margins entire or dentate, apex acute to obtuse, surfaces uniformly pubescent, trichomes cruciform and 3-rayed, adaxially sometimes mixed with coarse, simple ones. Cauline leaves 1–6; blade similar and equaling or smaller than basal. Fruiting pedicels slender, (1.5–)2–4(–6) mm. Flowers: sepals 0.5–1 × 0.3–0.7 mm; petals oblong, 1.5–3 × 0.5–1 mm; filaments 0.4–0.6 mm; anthers (0.05–)0.1–0.2(–0.25) mm. Fruits usually orbicular to obovate, rarely broadly oblong, 1-locular, not twisted; valves thin, veins sometimes prominent, usually pubescent, rarely glabrous, trichomes simple, to 0.5 mm, hooked (sometimes restricted to margins, or mixed with smaller, sessile, cruciform or 3-rayed ones); septum absent; ovules 2(–4) per ovary; style 0.05–0.2 mm. Seeds 1, (0.8–)0.9–1.1(–1.2) × (0.5–)0.7–0.9(–1) mm. 2n = 26.

Phenology: Flowering Feb–Jun.
Habitat: Open grassy slopes, grassy glades in woodlands, chaparral, sandy and gravelly flats, flood plains, rock outcrops, cliffs and ledges, on limestone, serpentine, sandstone, granitic and basaltic substrates
Elevation: 0-1800 m

Distribution

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B.C., Ariz., Calif., Idaho, Mont., Nev., Oreg., Wash., Mexico (Baja California).

Discussion

Records of Athysanus pusillus for Montana appear to be solely from Ravalli County, and for Nevada from Storey and Washoe counties.

References

None.

Lower Taxa

No lower taxa listed.