Astragalus nuttallianus DC. var. nuttallianus, turkey–pea, peavine, Nuttall’s milk–vetch. Annual, taprooted, not rosetted, several–stemmed at base, in range to 30 cm tall; shoots with cauline leaves, strigose and short–strigose.
Stems ± cylindric, < 2 mm diameter, with 3 faint ridges descending from leaf, green or aging purple–red, short–strigose with white, upward–pointing hairs.
Leaves helically alternate, odd–1–pinnately compound mostly with 6 pairs of lateral leaflets, petiole with pulvinus, with stipules; stipules 2, arising on node at pulvinus, narrowly triangular, ca. 4 mm long, green with membranous on margins at base, ciliate on leading margin, strigose with upward–pointed hairs on green tissue; petiole channeled above pulvinus; rachis channeled, to 20 mm long; petiolules 0.3—0.35 mm, glabrate; blades of leaflets ± elliptic to obovate, ca. 8 × 2.5—3 mm, oblique tapered at base, entire, notched at tip, with visible midrib raised on lower surface, upper surface with mostly appressed hairs, lower surface strigose with upward–pointing hairs. Leaves helically alternate, odd–1–pinnately compound mostly with 6 pairs of lateral leaflets, petiole with pulvinus, with stipules; stipules 2, arising on node at pulvinus, narrowly triangular, ca. 4 mm long, green with membranous on margins at base, ciliate on leading margin, strigose with upward–pointed hairs on green tissue; petiole channeled above pulvinus; rachis channeled, to 20 mm long; petiolules 0.3—0.35 mm, glabrate; blades of leaflets ± elliptic to obovate, ca. 8 × 2.5—3 mm, oblique tapered at base, entire, notched at tip, with visible midrib raised on lower surface, upper surface with mostly appressed hairs, lower surface strigose with upward–pointing hairs.
Inflorescence raceme, mostly with < 10 flowers, flowers helically alternate, short–strigose; peduncle 5–ridged, to 35 mm long, 0.6 mm diameter; rachis ridged having a ridge descending from each bractlet; bractlet sheathing, < 1 mm long, having translucent food bodies on margins; pedicel arching to hooked, 1—1.5 mm long, short–strigose with upward–pointing white and also reddish hairs. Inflorescence raceme, mostly with < 10 flowers, flowers helically alternate, short–strigose; peduncle 5–ridged, to 35 mm long, 0.6 mm diameter; rachis ridged having a ridge descending from each bractlet; bractlet sheathing, < 1 mm long, having translucent food bodies on margins; pedicel arching to hooked, 1—1.5 mm long, short–strigose with upward–pointing white and also reddish hairs.
Flower bisexual, bilateral, pealike (papilionaceous), 4—6 mm across; calyx 5–lobed, 3.6—3.9 mm long; tube bell–shaped, 2 × 1.2 mm, green but reddish on upper half, strigose; lobes acuminate, 1.7—3 mm long, with raised midvein; petals 5; banner ca. 10 mm long, claw 1—1.5 mm long, white, limb roundish with notch at top, ca. 8.5 × 6 mm, violet with white center and radiating veins violet, strongly reflexed; wings 2, ca. 8 mm long, < banner, claw 2 mm long, white, limb obovate, ca. 6 × 2 mm + backward–pointing lobe < 1 mm long, white and light violet; keel of 2 petals fused almost to base of claws and nearly to tip of limbs on lower edge, 6.5—7 mm long, claws slender, 2 mm long, white, with open notch between them at base, limbs oblanceolate, ca. 5.5 × 2.2 mm including backward–pointing triangular lobes 0.5 mm long, dark violet with purple–red approaching tip; stamens 10, diadelphous (9 fused + 1 free); filament sheet 5 mm long, white, free filament portions 2—2.5 mm long; anthers dorsifixed, dithecal, 0.3 mm long, orange, longitudinally dehiscent; pollen orange; pistil 1, ca. 7 mm long, with short stalk 0.5 mm long; ovary superior, oblong, ca. 4.5 mm long, green, 2–chambered, each chamber with ca. 6 ovules attached to upper side; style 2—2.5 mm long, pale green, curved above midpoint, glabrous; stigma terminal, minute
Fruit pod (legume), short stalk (stipe) 0.5 mm long, dehiscent, ca. 10–seeded, 2–valved, 2–chambered separated by papery septum, cylindric and straight to slightly curved, 15—22 × 2—2.3 mm, brown, with conspicuously raised veins mostly ⊥ on valve, somewhat 4–sided in ×–section, with point at tip, seeds mostly 4—6 per chamber.
Seed prismatic and rectangular to parallelogram in surface view, ca. 1 × 0.8 × 0.6 mm, olive–brown with black spots, hard.
A. C. Gibson