Dalea tenuis (Coult.) Shinners, stanfield prairie–clover. Perennial herb, several—many–stemmed at base, initially long shoots forming lateral branch at each leafy node, with terminal inflorescences to 30 cm tall; shoots with feathery cauline leaves clustered within 20 mm of principal stem, foliage gland–dotted on lower surfaces, aromatic when crushed, essentially glabrous except leaf bases and stipules.
Stems ± cylindric, to 1.5 mm diameter, tough, striped green or with red.
Leaves helically alternate, pinnately 3–foliolate, petiolate with pulvinus, with stipules; stipules 2, fused to base of petiole (below pulvinus), acuminate, 0.8—3 mm long, mostly red above base with short hairs or fringed on outer margin and the decurrent leaf base; petiole < 6—13 mm long, pulvinus < 1 mm long, above pulvinus channeled, slender, light green; petiolules canoelike, 0.6—1 mm long, pale green; rachis channeled, < 4 mm long; blades of leaflets linear, < 5—15 × 0.5—1 mm, entire, prow–shaped with short point at tip, 1–veined, folded upward from midrib (inrolled), upper surface glaucous, lower surface dark green and somewhat glossy, minutely gland–dotted.
Inflorescence headlike spike, terminal on long peduncle, many–flowered, before anthesis conic, with spreading flowers ca. 15 mm wide and in young fruit (7—)8—9(—10) mm wide, bracteate, densely soft–hairy; peduncle cylindric, to 100 mm long, 1 mm diameter, tough, flexible, sometimes striped purplish red, glabrous; axis densely soft–hairy; bractlet subtending flower clasping calyx, boat–shaped with tail–like tip and somewhat keeled, 3—3.5 mm long, tough, red–brown with green triangle at base, soft short–ciliate to midpoint and fringed above and glandular hairy along tip, soft–hairy on back where not exposed, persistent in fruit.
Flower bisexual, bilateral, ca. 10 mm across; calyx 5–lobed, overall angular–obovoid, 2.5—3 mm long, green; tube somewhat 3–sided and compressed by adjacent flowers and bractlets, ca. 2 × 2 mm, white with exposed surface green, having 3 hairy ridges to sinuses of upper lobes, densely soft–hairy (sericeous) with downward–pointing hairs; upper 2 lobes deltate, 1.3—1.5 mm wide, lower 3 lobes ovate, 0.8—1 mm wide, green, with upward–pointing hairs above midpoint; petals 5, banner free, wings and keel petal fused to stamens alternating with free filaments, clawed, light pink–purple; banner claw ca. 3 mm long, white but light pink–purple approaching limb; limb inversely heart–shaped, 2 × 2—2.2 mm, cupped outward; wings ovate with short claw but limb asymmetric at base (hastate) larger toward banner, 3 × 1.2—1.3 mm, minutely bumpy on upper margin; keel petals 2, oblong–lanceolate with short claw, 3 × 1.1—1.3 mm, obtuse to broadly acute at tip; stamens 5, monadelphous (5 fused as a sheet), sheet at top having 5 exserted filaments alternating with 4 exserted petals (2 wings + 2 keel petals, sometimes interpreted as staminodes); filament sheet open with ovary bulging out on upper side, 3 mm long, white, 9–ribbed; free filaments spreading, 4.5—5 mm long, pink–purple but paler next to sheet; anthers dorsifixed, dithecal, 1—1.1 mm long, bright yellow to orange–yellow, longitudinally dehiscent; pollen yellow; nectary tissue at base of ovary, nectar–producing, nectar thin; pistil 1, 9—10 mm long; ovary superior, ovoid compressed side–to–side but more enlarged to upper side, ca. 1.5 × 0.8 mm, white with some green, mostly glabrous with erect hairs near top, having inconspicuous glands on faces, 1–chambered with 2 ovules attached to upper side; style bent ca. 1.5 mm from base, white, having hairs to bend; stigma terminal.
Fruit pod (legume), indehiscent and shed within calyx and scarious with filament sheet, 1–seeded, hatchet–shaped constricted around seed above midpoint, 2.5—3 × 1.5 mm, brown around seed and tannish and blotchy below midpoint.
Seed ca. 1 × 1 mm, dark brown but difficult to separate from fruit wall.
A. C. Gibson