Streptanthus petiolaris

A. Gray

Mem. Amer. Acad. Arts, n. s. 4: 7. 1849.

Synonyms: Arabis petiolaris (A. Gray) A. Gray Erysimum petiolare (A. Gray) Kuntze Streptanthus brazoensis Buckley
Treatment appears in FNA Volume 7. Treatment on page 719. Mentioned on page 701, 720.

Annuals; pilose proximally, glabrous distally. Stems unbranched or branched distally, 2–12 dm. Basal leaves subrosulate; long-petiolate; blade lyrate-pinnatifid, oblanceolate in outline, 3–21 cm, margins (of lobes) dentate, (surfaces pilose). Cauline leaves (petiolate); blade lyrate-pinnatifid, hastate, or (distally) linear lanceolate, 2–14 cm × 5–70 mm, margins (distally) entire. Racemes ebracteate, (lax). Fruiting pedicels divaricate to ascending, (straight or curved upward), 7–13 mm. Flowers: calyx subcampanulate; sepals lavender, (oblong), 3–4.5 mm, not keeled; petals white to lavender, 4–8 mm, blade 1.5–4 × 1.5–2 mm, margins not crisped, claw 2.5–4 mm, narrower than blade; stamens tetradynamous; filaments: median pairs (distinct), 2.5–4 mm, lateral pair 1.5–3 mm; anthers (all) fertile, 0.5–1 mm; gynophore 0.3–0.7 mm. Fruits suberect to divaricate-ascending, slightly torulose, straight, strongly flattened, 4–9 cm × 3.5–5 mm; valves each with obscure midvein; replum straight; ovules 28–50 per ovary; style 0.5–2.7 mm; stigma slightly 2-lobed. Seeds orbicular, 3.5–5 mm diam.; wing 0.8–1.4 mm wide, continuous. 2n = 28.


Phenology: Flowering Mar–May.
Habitat: Thickets, roadsides, canyons, grassy grounds, bluffs, knolls, rocky limestone prairies, juniper-oak woods

Discussion

Streptanthus petiolaris was treated by other North American authors under Arabis, but the species does not belong to that genus (I. A. Al-Shehbaz 2003b) or to Boechera; it has 2n = 28, a chromosome number universal in Streptanthus and not found in any species of Arabis or Boechera, and it lacks the branched trichomes characteristic of those genera.

Selected References

None.

Lower Taxa

None.
... more about "Streptanthus petiolaris"
Ihsan A. Al-Shehbaz +
A. Gray +
Thickets, roadsides, canyons, grassy grounds, bluffs, knolls, rocky limestone prairies, juniper-oak woods +
Flowering Mar–May. +
Mem. Amer. Acad. Arts, n. s. +
Arabis petiolaris +, Erysimum petiolare +  and Streptanthus brazoensis +
Streptanthus petiolaris +
Streptanthus +
species +