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scurfpea, subterranean Indian breadroot

largebract Indian breadroot, tallbread scurfpea

Habit Herbs usually acaulescent, rarely subacaulescent, to 25 cm, pubescent throughout and eglandular or sparsely glandular with pale, sunken obscure glands on leaflets and/or calyx tubes only. Herbs caulescent, to 100+ cm, mostly glandular throughout, strigose becoming glabrate.
Stems

short-erect, with decumbent laterals, decumbent stems 0–6 cm, overtopped by leaves, leaves clustered;

pseudoscapes usually 1, unbranched, rarely 2, 0.5–9.5 cm;

cataphylls 5–20 mm.

1+, decumbent to erect-ascending, much branched, leaves dispersed along stems;

pseudoscapes rarely branched, 0–14 cm;

cataphylls 0–13 mm.

Leaves

palmately (3–)5-foliolate;

stipules persistent, linear-lanceolate to elliptic, 4–19 × 2–6 mm, appressed-pubescent;

petiole not obviously jointed basally, (20–)30–210 mm;

petiolules 1–3 mm;

leaflet blades elliptic to lanceolate, oblanceolate, or rhombic, 1–7.5 × 0.3–4 cm, base cuneate, apex acuminate, surfaces glabrate to sparsely pubescent.

palmately 3–5-foliolate;

stipules persistent, erect to reflexed, linear-lanceolate to lanceolate, 6–15 × 1–5 mm, glandular, pubescent;

petiole enlarged but not jointed basally, often canaliculate, 5–40 mm, sparsely strigose;

petiolules 1.5–3.5 mm;

leaflet blades oblanceolate to elliptic, oblong, or obovate, 2–4.8 × 0.5–2 cm, base cuneate, apex acute to obtuse or apiculate, surfaces abaxially pubescent, adaxially glabrous.

Inflorescences

disjointing in age at peduncle base, ovate to oblong;

rachis 0.5–6 cm, elongating slightly in fruit, nodes 3–15, 3 flowers per node, internodes crowded in flower, elongating to 25 mm in fruit;

bracts mostly persistent or very tardily deciduous, linear to oblanceolate or rhombic, 3–11 × 1.5–4.5 mm, appressed-pubescent.

persistent, ellipsoid to elongate;

rachis 1.5–8.5 cm, nodes (2–)6–17, 3 flowers per node, internodes to 13 mm;

bracts persistent, erect to reflexed, lanceolate, 4–17 × 1–6 mm, glandular, pubescent.

Peduncles

1–14 cm, shorter than subtending petiole, subappressed-pubescent.

0.6–15 cm, longer than subtending petiole, strigose.

Pedicels

1–5 mm.

2–3 mm.

Flowers

11–18 mm;

calyx weakly gibbous-campanulate in fruit, 9–15 mm abaxially, 6–14 mm adaxially, usually eglandular, very rarely glandular on tube, pubescent;

tube 2.5–6 mm;

lobes subulate or linear-lanceolate to lanceolate, abaxial 6–10 × 1.5–3(–4) mm, adaxial 4.5–9 × 1–1.5 mm;

corolla lavender to purple, banner paler, sometimes also marginally white, elliptic to obovate, 11–18 × 4–7 mm with claw 2–5 mm, wings 11–16 × 2–3 mm with claw 3.5–6 mm, keel 6–12 × 2–3 mm with claw 2.5–7 mm;

filaments 6–11 mm;

anthers round to elliptic, 0.3–0.5 mm;

ovary glabrous or pubescent apically, style pubescent basally.

12–22 mm;

calyx strongly gibbous-campanulate in fruit, 9–15 mm abaxially, 8–12 mm adaxially, glandular, pubescent;

tube 4–5.5 mm;

abaxial lobe lanceolate to elliptic, 8–19 × 2–3.5 mm, adaxial lobes lanceolate, 4–7 × 1–1.5 mm;

corolla blue, purple, or violet, banner broadly oblanceolate to obovate, 13–21 × 7–8 mm with claw 4–6 mm, wings 12–18.5 × 3–4 mm with claw 4–7.5 mm, keel 9–13 × 4–7 mm with claw 2.5–3 mm;

filaments 8–12 mm;

anthers elliptic, 0.5–0.6 mm;

ovary glabrous or pubescent and glandular on distal 1/4–1/3, style pubescent basally.

Legumes

ellipsoid-lanceoloid to oblong, 5–6.5 × 3–5 mm, eglandular, glabrous or slightly pubescent, beak 7–19 mm, exserted beyond calyx.

ovoid to obovate, 6–8 × 4–4.5 mm, glandular, pubescent distally, beak 1.5–2 mm, shorter than calyx.

Seed

red-brown or gray, globose-reniform, 4–5 × 2.5–3.5 mm, smooth to somewhat rugose.

reddish brown, reniform to globose, 3.5–4 × 4.5–5 mm.

2n

= 22.

Pediomelum hypogaeum

Pediomelum cuspidatum

Phenology Flowering spring–summer.
Habitat Grasslands, meadows, woodlands.
Elevation 50–1500 m. (200–4900 ft.)
Distribution
from USDA
w United States; c United States
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; KS; MT; NE; OK; SD; TX
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 3 (3 in the flora).

J. W. Grimes (1990) recognized three varieties under Pediomelum hypogaeum. Many specimens exist with intermediate traits that obscure strong delineations between taxa.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Pediomelum cuspidatum is one of the larger species in the genus, in spite of its procumbent habit with erect-ascending, copious lateral branches. Horizontal stems are often bicolored, purple adaxially and light green abaxially. It is variable, particularly in plant height, flower length, and inflorescence length.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Peduncles 1–3.5 cm, less than 1/2 as long as sub­tending petiole.
var. hypogaeum
1. Peduncles (1.7–)4–14 cm, more than 1/2 as long as subtending petiole.
→ 2
2. Peduncles appressed-pubescent; leaflet blades lanceolate to elliptic.
var. scaposum
2. Peduncles hirsute-villous; leaflet blades oblan­ceolate to rhombic.
var. subulatum
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Pediomelum Fabaceae > subfam. Faboideae > Pediomelum
Sibling taxa
P. argophyllum, P. aromaticum, P. californicum, P. canescens, P. castoreum, P. cuspidatum, P. cyphocalyx, P. digitatum, P. epipsilum, P. esculentum, P. humile, P. latestipulatum, P. linearifolium, P. megalanthum, P. mephiticum, P. palmeri, P. pariense, P. pentaphyllum, P. piedmontanum, P. reverchonii, P. rhombifolium, P. subacaule, P. tenuiflorum, P. verdiense
P. argophyllum, P. aromaticum, P. californicum, P. canescens, P. castoreum, P. cyphocalyx, P. digitatum, P. epipsilum, P. esculentum, P. humile, P. hypogaeum, P. latestipulatum, P. linearifolium, P. megalanthum, P. mephiticum, P. palmeri, P. pariense, P. pentaphyllum, P. piedmontanum, P. reverchonii, P. rhombifolium, P. subacaule, P. tenuiflorum, P. verdiense
Subordinate taxa
P. hypogaeum var. hypogaeum, P. hypogaeum var. scaposum, P. hypogaeum var. subulatum
Synonyms Psoralea hypogaea Psoralea cuspidata
Name authority (Nuttall) Rydberg in N. L. Britton et al.: N. Amer. Fl. 24: 21. (1919) (Pursh) Rydberg in N. L. Britton et al.: N. Amer. Fl. 24: 19. (1919)
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