Pediomelum
Pediomelum hypogaeum
breadroot, Indian breadroot
scurfpea, subterranean Indian breadroot
erect to ascending, decumbent, prostrate, or absent, glabrous or pubescent.
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.
clustered or alternate, usually palmate, pseudopalmate, or pinnately 3-foliolate (rarely phylloidal in P. rhombifolium), glandular or eglandular;
stipules present;
petiolate or sessile;
stipels absent;
leaflets (1–)3–7(or 8), blade margins entire, surfaces glabrous or pubescent.
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.
3–51-flowered, axillary, pseudoracemes;
bracts present.
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.
1–14 cm, shorter than subtending petiole, subappressed-pubescent.
1–5 mm.
papilionaceous;
calyx campanulate, usually enlarging through fruiting, rarely not enlarging, but flaring backwards and tearing along a lateral sinus (P. tenuiflorum), lobes 5, abaxial often enlarged;
corolla usually purple, blue, violet, or lavender, sometimes white, yellow or ochroleucous, rarely brick red or salmon-pink;
stamens 10, diadelphous;
anthers dorsifixed;
style arched to sharply reflexed.
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.
legumes, persistent on receptacle (except deciduous in P. tenuiflorum), sessile or short-stipitate, compressed, straight or curved, oblong, ellipsoid to lanceoloid, ovoid, obovoid, or globose, beaked, glabrous or pubescent, dehiscence circumscissile.
ellipsoid-lanceoloid to oblong, 5–6.5 × 3–5 mm, eglandular, glabrous or slightly pubescent, beak 7–19 mm, exserted beyond calyx.
1, globose to ellipsoid, oblong, or reniform, usually smooth;
hilum usually not surrounded by raised, white ridge.
red-brown or gray, globose-reniform, 4–5 × 2.5–3.5 mm, smooth to somewhat rugose.
= 11.
= 22.
Pediomelum
Pediomelum hypogaeum
Species 25 (25 in the flora).
Pediomelum has been classically recognized as Psoralea Linnaeus, a genus now circumscribed for psoraleoid species primarily of Africa. P. A. Rydberg (1919–1920) segregated Pediomelum from Psoralea based on the transverse dehiscence of the pod and a gibbous calyx, characters also supported as diagnostic of Pediomelum by J. W. Grimes (1990), along with a persistent fruit base following dehiscence. Molecular phylogenetic studies have also confirmed the natural grouping that is Pediomelum (A. N. Egan and K. A. Crandall 2008). Psoralidium was dissolved, with remaining species placed in Ladeania.
J. W. Grimes (1990) divided Pediomelum into three subgenera: subg. Leucocraspedon J. W. Grimes to accommodate two prostrate species with salmon, brick red, or yellowish flowers and a white ridge surrounding the hilum of the seed; subg. Pediomelum to accommodate those species that are usually caulescent and have a persistent inflorescence; and subg. Disarticulatum J. W. Grimes whose members are largely acaulescent and whose inflorescence becomes disjointed with age at the base of the peduncle. Molecular phylogenetic studies strongly support subg. Leucocraspedon, and somewhat follow membership of the other two subgenera, but not completely. Associations surrounding P. aromaticum and P. esculentum, in particular, are problematic (A. N. Egan and K. A. Crandall 2008, 2008b).
Endemism is high in Pediomelum with most species having restricted geographical ranges. This, coupled with habitat degradation from grazing and urbanization, has resulted in a number of Pediomelum species being listed as rare, threatened, or endangered (K. S. Walter and H. J. Gillett 1998). The rapid and recent evolutionary diversification of Pediomelum may have contributed to the level of endemism within the group (A. N. Egan and K. A. Crandall 2008b) and has made species delimitation within the genus difficult. Considerable differences of opinion exist as to what criteria should be used for species delimitation and how many species exist within the genus, particularly for those in the southwestern United States.
Several species of Pediomelum are of historical economic importance. Pediomelum esculentum was once an important starch source for Native American tribes of the Great Plains, as recorded on the historic Lewis and Clark Expedition (Mer. Lewis and W. Clark 2003).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
1. Stems usually prostrate, rarely decumbent, leaves dispersed uniformly along stems; corollas usually brick red to salmon-pink, or with whitish green or yellow base and salmon-pink apex, or yellow throughout, rarely white; hilum surrounded by raised, white ridge. | → 2 |
2. Leaves usually pinnately 3-foliolate, rarely reduced to phyllodes; corollas usually brick red to salmon-pink, rarely white. | P. rhombifolium |
2. Leaves mostly pseudopalmately 5-foliolate, sometimes proximalmost leaves pinnately 3-foliolate; corollas whitish green to yellow with salmon-pink apex, or yellow throughout. | P. palmeri |
1. Stems erect or absent and leaves clustered or dispersed along stems, if decumbent lateral stems present, then leaves and inflorescences clustered at base of plant or tips of lateral stems; corollas usually blue, violet, lavender, or purple, sometimes ochroleucous, rarely white, cream, or yellowish; hilum not surrounded by raised, white ridge. | → 3 |
3. Herbs acaulescent or subacaulescent (sometimes with clustered leaves), or shortly caulescent (main stem to 13 cm), sometimes with decumbent branches from basal nodes, and subtended by cataphylls. | → 4 |
4. Leaves usually 3-foliolate, rarely 5-foliolate, adaxial surface with veins conspicuously hairier than remaining surface. | → 5 |
5. Leaves palmate; flowers 8–12.5 mm; s Utah. | P. pariense |
5. Leaves pinnate; flowers 12–20 mm; w Texas. | P. humile |
4. Leaves usually 5–7-foliolate, rarely 1–3-foliolate (rarely 8-foliolate in P. megalanthum), adaxial surface veins not conspicuously hairier than remaining surface. | → 6 |
6. Adaxial calyx lobes 1–2 mm; Alabama, Georgia, Tennessee. | P. subacaule |
6. Adaxial calyx lobes 2+ mm; c, w North America. | → 7 |
7. Herbs eglandular or sparsely glandular with obscure pale, sunken glands on one or both leaflet surfaces or rarely on calyx tube. | → 8 |
8. Stipules and bracts glabrate to sparsely pubescent with semi-erect hairs; inflorescences persistent (not disjointing at base of peduncle in fruit); calyx strongly gibbous-campanulate in fruit; seeds brown. | P. esculentum |
8. Stipules and bracts appressed-pubescent; inflorescences disjointing in age at base of peduncle; calyx weakly gibbous-campanulate in fruit; seeds red-brown or gray. | P. hypogaeum |
7. Herbs mostly glandular throughout with obvious blond to dark brown glands. | → 9 |
9. Calyx tubes 5–8(–10) mm. | → 10 |
10. Leaflet blade surfaces adaxially glabrous or sparsely strigose only along base of veins. | P. epipsilum |
10. Leaflet blade surfaces adaxially pubescent. | P. megalanthum |
9. Calyx tubes 2–5 mm. | → 11 |
11. Some leaves pseudopalmate; abaxial calyx lobe broadly oblanceolate, 3.5–4.5 mm wide; seeds rugose. | → 12 |
12. Leaflet blades oblanceolate or orbiculate to elliptic, apex rounded or retuse; flowers 9–13 mm; calyx lobes 4–5 mm. | P. castoreum |
12. Leaflet blades lanceolate, rhombic, or slightly oblanceolate, apex acute, mucronate; flowers 14–18 mm; calyx lobes. | P. pentaphyllum |
11. All leaves palmate; abaxial calyx lobe linear-lanceolate to oblanceolate or elliptic, 1.5–3.5 mm wide; seeds smooth. | → 13 |
13. Herbs often with decumbent lateral stems; peduncles appressed-spreading pubescent; calyx tube 2–3 mm; California. | P. californicum |
13. Herbs rarely with decumbent lateral stems; peduncles pilose, hairs spreading, retrorse or antrorse; calyx tube 2.5–5 mm; nw Arizona, se Nevada, sw Utah. | → 14 |
14. Peduncles (2–)4–8(–10) cm; calyx tube 2.5–4 mm; nw Arizona, se Nevada, sw Utah. | P. mephiticum |
14. Peduncles (0.5–)1–5.5(–6) cm; calyx tube (3.5–)4–5 mm; Mohave and Yavapai counties, Arizona. | P. verdiense |
3. Herbs caulescent, leaves dispersed along stems, branches subtended by leaves. | → 15 |
15. Petioles, when present, usually shorter than petiolules. | → 16 |
16. Inflorescences loose (much of rachis exposed); petiolules 5–9 mm. | P. canescens |
16. Inflorescences crowded (rachis usually concealed); petiolules 1.8–3 mm. | P. piedmontanum |
15. Petioles longer than petiolules. | → 17 |
17. Herbs eglandular throughout. | P. esculentum |
17. Herbs glandular (or only on adaxial leaflet surfaces in P. digitatum). | → 18 |
18. Stems decumbent to erect-ascending or suberect. | → 19 |
19. Inflorescences umbellate or subcapitate, rarely reduced to a single flower; flowers (7–)8–11(–12) mm; desert communities of Arizona, Colorado, and Utah. | P. aromaticum |
19. Inflorescences ellipsoid to elongate, flowers numerous; flowers 12–22 mm; grasslands, meadows, and woodland communities of midwestern United States. | P. cuspidatum |
18. Stems strongly erect. | → 20 |
20. Flowers 5–6 mm; calyx tube 1–1.5 mm. | P. tenuiflorum |
20. Flowers 7–26 mm; calyx tube 2–8 mm. | → 21 |
21. Flowers 7–11 mm; calyx tube 2–4 mm. | → 22 |
22. Herbs mostly silvery-sericeous; pedicels 0.5–1 mm; corollas deep blue. | P. argophyllum |
22. Herbs strigose, glabrate, or appressed-canescent, but not silvery; pedicels 1–10 mm; corollas purple to violet, blue-violet, blue-lavender, white, or white suffused with purple. | → 23 |
23. Herbs eglandular except on adaxial leaflet surfaces; pedicels 1–3 mm. | P. digitatum |
23. Herbs glandular throughout; pedicels 3.5–10 mm. | P. linearifolium |
21. Flowers 12–26 mm, calyx tube 4–8 mm. | → 24 |
24. Stems decumbent to erect-ascending; legumes with beak 1.5–2 mm. | P. cuspidatum |
24. Stems erect; legumes with beak 2–6 mm. | → 25 |
25. Herbs 5–45 cm; calyx tube 6–8 mm. | P. latestipulatum |
25. Herbs to 150 cm; calyx tube 4–5 mm. | → 26 |
26. Inflorescences globose-ovoid (compact), with rachis 0.5–0.7 cm; bracts orbiculate, 6–13 mm wide; pedicels 3.5–5 mm. | P. reverchonii |
26. Inflorescences oblong to elliptic, with rachis 1.5–7 cm; bracts mostly oblanceolate to obovate, 1.5–4 mm wide; pedicels 1.5–2 mm. | P. cyphocalyx |
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 |
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