Pediomelum humile |
Pediomelum subacaule |
|
---|---|---|
Rydberg's Indian breadroot, Rydberg's scurfpea |
Nashville breadroot, white-rim scurfpea |
|
Habit | Herbs acaulescent, to 20 cm, mostly glandular and pubescent throughout. | Herbs acaulescent or subacaulescent, to 20 cm, eglandular except leaves or rarely stipules and bracts, pubescent. |
Stems | absent, leaves clustered; pseudoscapes 5–7 cm (when present); cataphylls 7–9 mm, striate, clustered apically. |
absent, leaves clustered; pseudoscapes erect, 3–10 cm, usually 1, sometimes to 6, rarely branched proximally; cataphylls 10–20 mm (when present). |
Leaves | pinnately 3-foliolate; stipules persistent, lanceolate to oblanceolate-oblong, 5–7(–12) × 2.5–3 mm, stramineous, eglandular, glabrous; petiole swollen proximally or not, not jointed, (30–)50–120 mm; petiolules 2 mm; leaflet blades orbiculate to obovate-trullate, lateral 2 usually asymmetrical, 1.5–2.5(–3.2) × 1–2.4 cm, base broadly cuneate or truncate, apex broadly acute, surfaces abaxially white-pubescent, adaxially white-hirsute along veins and margins. |
palmately 5–7-foliolate; stipules often fragmented on plant, partly connate, ovate, 11–24 × 11–16 mm, scarious, usually eglandular, sparsely pubescent; petiole jointed basally, 40–150(–190) mm, shorter than peduncle, hirsute-villous; petiolules 1–2.5 mm; leaflet blades oblanceolate to elliptic, 1.5–4.5(–6) × 0.5–1.3(–1.8) cm, base cuneate, apex acuminate to obtuse, surfaces glandular, abaxially pubescent, adaxially sparsely so, usually along margins. |
Inflorescences | disjointing in age at peduncle base, ovate to elliptic; rachis 1.4–1.6 cm, crowded, nodes 4–7, 3 flowers per node; bracts persistent, caudate-lanceolate, 5–8 × 2–3.5 mm, pubescent throughout or only at apex. |
disjointing in age at peduncle base, long-ovoid; rachis 2.5–9.5 cm, elongating through fruiting, nodes 4–11(–15), 3 flowers per node, internodes 1–5 mm, elongating to 25 mm in fruit; bracts persistent, orbiculate to lanceolate, 7–14 × 2–7 mm, margins pubescent, apex sometimes caudate or emarginate, becoming papery and veined in age. |
Peduncles | 2–10 cm, shorter than subtending petiole, glabrous proximally, pubescent distally. |
4–14 cm (8–19 cm in fruit), longer than subtending petiole, setose. |
Pedicels | 1–3 mm. |
1–2 mm. |
Flowers | 12–20 mm; calyx gibbous-campanulate in fruit, 10–15(–17) mm, pubescent throughout or teeth only; tube 5–7 mm; lobes linear or linear-lanceolate, abaxial 8–8.5 × 1–1.5 mm, adaxial 6–7.5 × 0.5–1 mm; corolla white and blue-purple, banner white to pale purple, oblanceolate, 15–17 × 6–7 mm with claw 4.5–5.5 mm, wings blue-purple, 12–14 × 2.5–3 mm with claw 5.5–6.5 mm, keel dark purple, 14–16 × 2.5–3 mm with claw 8.5 mm; filaments 16 mm; anthers elliptic, 0.7 mm; ovary glabrous, style glabrous. |
10–15(–22) mm; calyx weakly gibbous-campanulate in fruit, 6–10 mm abaxially, 5–8 mm adaxially, glabrate and eglandular on gibbous portion, sparsely setose and glandular distally; tube stramineous, 4.5–6 mm; lobes triangular, abaxial 2–4 × 2 mm, adaxial 1–2 × 1 mm; corolla dark blue to purple, banner oblanceolate to oval, 13–23 × 4–5 mm with claw 5–6 mm, wings 12–18 × 2–3 mm with claw 5–7 mm, keel 10–15 × 2–3 mm with claw 2–3 mm; filaments 10–12 mm; anthers obovate, 0.3 mm; ovary pubescent apically, style pubescent basally. |
Legumes | oblong-ellipsoid, 5–7 × 3.5–4 mm, eglandular, pubescent apically, beak 4–5 mm, about as long as calyx. |
globose to ovoid, 6–7 × 4–5 mm, eglandular, sparsely pubescent apically, beak triangular, 4–6 mm, exserted beyond calyx. |
Seed | black, ellipsoid-reniform, 3.5–6 × 2.5–4 mm. |
gray-brown to red-brown, obovoid-reniform, 5–6 × 3–4 mm. |
2n | = 22. |
|
Pediomelum humile |
Pediomelum subacaule |
|
Phenology | Flowering spring. | Flowering spring. |
Habitat | Shallow, rocky clay or limestone soils, shortgrass prairies, shrublands. | Calcareous soils, cedar glades. |
Elevation | 700–2000 m. (2300–6600 ft.) | 200–1500 m. (700–4900 ft.) |
Distribution |
TX; Mexico (Coahuila) |
AL; GA; TN
|
Discussion | Pediomelum humile, historically known from along the Rio Grande in Texas (Val Verde County) and Mexico, is very rare and on the verge of extinction. Several known populations have been destroyed by urban development in the recent past. The few populations in existence today are located near Del Rio and are all in danger of extirpation due to human influences. Pediomelum humile is in the Center for Plant Conservation’s National Collection of Endangered Plants. Psoralea humilis (Rydberg) J. F. Macbride 1922, an illegitimate name (not Miller 1768), pertains here. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Pediomelum subacaule is known from Colbert and Franklin counties in Alabama, Catoosa County in Georgia, and Davidson, Maury, Rutherford, and Wilson counties in Tennessee. Pediomelum subacaule is quite distinct and disjunct from its fellow members of subg. Disarticulatum, this evidenced by its large, partly connate stipules and short, broad calyx lobes, and by being the only species in the subgenus east of the Mississippi River. Pediomelum subacaule is restricted to limestone soil in open cedar glades. Although P. subacaule is well established in the protected cedar glades of Tennessee, its historical range is shrinking due to habitat loss. Several historical sites that were, or still are, active limestone quarries have no remaining evidence of P. subacaule, particularly in Alabama and Georgia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 11. | FNA vol. 11. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Psoralea rydbergii | Psoralea subacaulis, Lotodes subacaulis |
Name authority | Rydberg in N. L. Britton et al.: N. Amer. Fl. 24: 24. (1919) | (Torrey & A. Gray) Rydberg in N. L. Britton et al.: N. Amer. Fl. 24: 20. (1919) |
Web links |