Pediomelum esculentum

Herbs usually caulescent, rarely subacaulescent to acaulescent, to 50 cm, eglandular and pubes­cent throughout. Stems erect, usually unbranched, some­times branched basally, leaves dis­persed along stem and arising nearly perpendicular to it; pseudoscapes 0.5–2 cm; cataphylls 0.5–15 mm, striate. Leaves palmately (3–)5-foliolate; stipules persistent, broadly lanceolate proximally to linear-lanceolate distally, 10–20 × 2–8 mm, stramineous basally, eglandular, glabrate to sparsely pubescent, hairs semi-erect; petiole not jointed basally, (2–)30–100(–150) mm; petiolules 1.5–4 mm; leaflet blades elliptic to oblanceolate, 2–4(–6) × 0.7–2.3 cm, base attenuate to cuneate, apex broadly acute to rounded or retuse, surfaces abaxially pubescent, adaxially glabrate except on midvein. Peduncles (0.5–)5–12(–15) cm, shorter than subtending petiole, pilose. Inflorescences persistent (not disjointing at base of peduncle in fruit), elliptic to oblong; rachis 1.6–7 cm, elongating slightly in fruit, nodes (6–)8–15, (2 or)3 flowers per node; bracts persistent, oblanceolate to elliptic, 5–15 × (0.5–)4–9 mm, glabrate to sparsely pubescent, hairs semi-erect. Pedicels 1–3 mm. Flowers 12–20 mm; calyx strongly gibbous-campanulate in fruit, 13–16 mm abaxially, 12–14 mm adaxially, eglandular, pubescent; tube 5–6 mm; lobes linear or linear-lanceolate to elliptic, abaxial 7.5–10 × 2–2.5 mm, adaxial 4–7 × 1–1.5 mm; corolla violet to blue-purple, banner sometimes paler, oblanceolate, 17–18 × 6 mm with claw 7–8 mm, wings 15–16.5 × 3–3.5 mm with claw 6–6.5 mm, keel 12–12.5 × 3 mm with claw 6–6.5 mm; filaments 11–14 mm; anthers elliptic, 0.5 mm; ovary pubescent apically, style glabrous apically. Legumes oblong, 4–6 × 2.5–3.5 mm, eglandular, pubescent, beak 9–13(–16) mm, exserted beyond calyx. Seed brown, reniform, 4 × 3 mm, somewhat rugose. 2n = 22.

Phenology: Flowering late spring–summer.
Habitat: Prairies, grasslands, open pine woodlands.
Elevation: 500–2000 m.

Distribution

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Alta., Man., Sask., Ark., Colo., Ill., Iowa, Kans., Minn., Mo., Mont., Nebr., N.Mex., N.Dak., Okla., S.Dak., Tex., Wis., Wyo.

Discussion

Pediomelum esculentum was once one of the main sources of starch for Native American tribes of the Great Plains, eaten fresh, boiled, dried, or ground into flour and used as a thickening agent. Use of the root for food and barter was documented by Lewis and Clark on their historic expedition across the United States (Mer. Lewis and W. Clark 2003).

Pediomelum esculentum ranges in morphology from strongly caulescent to acaulescent with no apparent geo­graphical structuring in this most widespread species. J. W. Grimes (1990) placed this species in subg. Pediomelum due to its persistent inflorescences. Molecular phylogenetic and network analyses suggest a split affinity for P. esculentum between both subgenera, suggesting that this may be an intermediate form and bridge between his subgenera or the groupings suggested by D. J. Ockendon (1965) based on habit—groupings somewhat supported by molecular phylogenies (A. N. Egan and K. A. Crandall 2008, 2008b).

Selected References

None.

Lower Taxa

None.