Draba bifurcata

Biennials or, rarely, perennials; caudex simple or branched; not scapose. Stems branched or unbranched, 1–3.9 dm, pubescent throughout or proximally, trichomes simple, 0.3–1.4 mm, often with smaller, 2 (or 3) -rayed ones. Basal leaves (soon withered); rosulate; petiolate; petiole ciliate, (trichomes simple, 0.4–1.1 mm); blade oblanceolate to spatulate, 1–7 cm × 2–12 (–26) mm, margins entire or dentate (pubescent as petiole), surfaces pubescent, abaxially with simple trichomes, 0.6–1.1 mm, and stalked, 2- (or 3-) rayed ones, often smaller, adaxially with subsetiform, simple trichomes, 0.5–1.2 mm (rarely with fewer, stalked, 2-rayed ones). Cauline leaves (2–) 6–15; sessile; blade lanceolate to ovate or oblong, margins dentate, surfaces pubescent as basal. Racemes 10–51-flowered, ebracteate, elongated in fruit; rachis glabrous or pubescent as stem, not flexuous. Fruiting pedicels horizontal to divaricate, straight, 4–15 mm, glabrous or pubescent, trichomes simple and 2-rayed. Flowers: sepals ovate, 2.5–3.2 mm, pubescent, (trichomes simple and short-stalked, 2-rayed); petals yellow, oblanceolate, 4.5–6.5 × 1.5–2 mm; anthers oblong, 0.8–1.1 mm. Fruits elliptic-lanceolate, twisted (1 turn or plane), flattened, 6–10 × 2–2.5 mm; valves glabrous or sparsely puberulent, trichomes simple, 0.05–0.15 mm; ovules 14–20 per ovary; style (1–) 2–3 mm. Seeds oblong, 1.1–1.4 × 0.7–0.9 mm.

Phenology: Flowering Jun–Jul.
Habitat: Rocky areas, damp shady ravines, aspen-spruce communities
Elevation: 1800-3600 m

Ariz.

Discussion

Draba bifurcata is distinguished from other North American species by a combination of yellow flowers with styles (1–)2–3 mm and almost exclusively simple trichomes on the abaxial surface of cauline leaf blades. It is known only from Chiricahua, Santa Catalina, and White mountains in Apache, Cochise, and Pima counties.

Selected References

None.

Lower Taxa