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Chihuahua scurfpea, small Indian breadroot

Habit Herbs subacaulescent, to 30 cm, mostly glandular (with obvious blond to dark brown glands) and appressed-spreading pubescent throughout.
Stems

mostly very short-erect, sparsely branched, with leaves clustered at base, rarely with decumbent lateral stems 0–15 cm, with leaves and inflorescences in terminal clusters;

pseudoscapes 0–4 cm;

cataphylls 7–15 mm (when present), apically emarginate.

Leaves

palmately or pseudopalmately 5(or 6)-foliolate, sometimes with 2 leaflets distal to others;

stipules persistent, lanceolate to linear, 9–15 × 5 mm, strigose-tomentose;

petiole jointed basally, 60–150 mm, strigose-tomentose;

petiolules 1.5–2 mm;

leaflet blades lanceolate, rhombic, or slightly oblanceolate, 2–5.5 × (1.5–)2–3.2 cm, base cuneate, margins undulate, apex acute, mucronate, surfaces glandular and pubescent.

Inflorescences

disjointing in age at peduncle base, globose to long-ovoid;

rachis 2–4.5 cm, nodes 6–9, 3 flowers per node;

bracts persistent to tardily deciduous, lanceolate to elliptic, often ensiform, 5–7 × 2–3 mm, membranous in age, strigose.

Peduncles

(3–)4–9.5 cm, equal to or shorter than subtending petiole, appressed-pubescent.

Pedicels

2–3 mm.

Flowers

14–18 mm;

calyx gibbous-campanulate in fruit, 14–16 mm abaxially, 11–12 mm adaxially, glandular, strigose;

tube 4–5 mm;

abaxial lobe broadly oblanceolate, 10–12 × 3.5–4 mm, adaxial lobes linear-lanceolate, 7–8 × 1–1.5 mm;

corolla white to purple, banner white to lavender, paler than other petals, lanceolate to elliptic, 15–17 × 6–7 mm with claw 4–5 mm, wings 15–16 × 3–3.5 mm with claw 6 mm, keel 9–12 × 3 mm with claw 6–7 mm;

filaments 8.5–10.5 mm;

anthers round-elliptic, 0.3 mm;

ovary pubescent apically, style pubescent basally.

Legumes

ellipsoid-oblanceoloid, 7–8 × 4–5 mm, eglandular, pubescent, beak broad, flat, 10–15 mm, barely exserted beyond calyx.

Seed

gray-green to brown, oblong-reniform, 5–6 × 3–4 mm, rugose.

Pediomelum pentaphyllum

Phenology Flowering spring–early summer.
Habitat Desert grasslands.
Elevation 1500–2000 m. (4900–6600 ft.)
Distribution
from FNA
AZ; NM; TX; Mexico (Chihuahua)
[BONAP county map]
Discussion

A history of the confusing nomenclature of Pediomelum pentaphyllum was given by P. Tonne (2000). The name was misapplied by P. A. Rydberg (1919–1920); the plant that Rydberg described as P. pentaphyllum was actually P. palmeri; the plant denoted here as P. pentaphyllum was called P. trinervatum Rydberg. J. W. Grimes (1990), before completion of his monograph, erroneously annotated several P. pentaphyllum specimens as P. trinervatum.

Pediomelum pentaphyllum is rare, with only a few confirmed populations in Arizona (Cochise and Graham counties) and New Mexico (Hidalgo County); it was also collected in Texas (Presidio County), and Chihuahua, Mexico (P. Tonne 2000), but may be extirpated in those states.

Pediomelum pentaphyllum is said to have been used by Native Americans and indigenous Mexicans as a fever reducer, the use of which may have contributed historically to its spread through cultivation. It is uncertain as to why P. pentaphyllum has declined, but causes may include over-collecting, grazing, and herbicide application (WildEarth Guardians, https://pdf.wildearthguardians.org/site/DocServer/petition_scurfpea.pdf?docID=624&AddInterest=1103).

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

Source FNA vol. 11.
Parent taxa 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. hypogaeum, P. latestipulatum, P. linearifolium, P. megalanthum, P. mephiticum, P. palmeri, P. pariense, P. piedmontanum, P. reverchonii, P. rhombifolium, P. subacaule, P. tenuiflorum, P. verdiense
Synonyms Psoralea pentaphylla
Name authority (Linnaeus) Rydberg in N. L. Britton et al.: N. Amer. Fl. 24: 23. (1919)
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