Astragalus quinqueflorus S. Watson, Proc. Amer. Acad. Arts

Castillón, Eduardo Estrada, Quintanilla, José Ángel Villarreal, Delgado-Salinas, Alfonso & Rebman, Jon P., 2023, The genus Astragalus (Leguminosae: Papilionoideae: Galegeae) in Mexico, Phytotaxa 586 (1), pp. 1921-1935 : 1921-1935

79. Astragalus quinqueflorus S. Watson, Proc. Amer. Acad. Arts 21: 450. 1886

Type:— MEXICO, Chihuahua, on the hills and plains near Chihuahua, April 1885, Pringle 234 (holotype: GH 00059432 digital image; isotype: US 00001533 digital image!, NY 00005836!, UVMVT 024924 digital image!, F 0058946 F digital image!, MO-128353 digital image!) .

Phaca quinquiflora (S. Watson) Rydb., N. Amer. Fl. 24(6): 361. 1929.

Perennial, but of short duration. Stems short, thin, radial, many, up to 15 cm long, the trichomes up to 0.6 mm long, straight, silvery or ashy. Stipules 1.3–3.2 mm long, amplexicual to semi-clasping, not connate, lanceolate to triangular or ovate. Leaves 2–17 cm long, leaflets 5–11, the pairs well separated from each other, 2–25 mm long, linear to oblong, obtuse or retuse, folded, subequal or the distal one the larger, adaxially glabrate or sub-glabrous. Peduncles 1–17 cm long; the racemes 3–4 cm long, lax, flowers 1–7. Flowers whitish, with purple tones; the calyx 2.4–3.6 × 1.3–1.6 mm, strigose, trichomes white, the tube 1.5–2 mm long, the teeth 0.6–1.7 mm long, subulate; the banner 4.4–5.4 × 2.6–3.8 mm, obovate to rhombic, recurved, slightly retuse; the wings 4–4.6 × 1–1.3 mm, the claw 1.5–1.8 mm long, the blade 2.9–3.3 mm long, oblong to oblanceolate, oblique-incurved; the keel 3.2–3.8 × 1.3–1.8 mm, the claw 1.2–1.8 mm long, the blade 1.7–2.1 mm long, strongly incurved. Pod 6–11 × 3–4.5 mm, sessile, deflexed, frequently humistrate with age, triquetrous, sometimes inflated-trigonous, oblique, ovoid, oblongo to elliptic, straight o gently incurved, basally rounded, distally contracted in a short subulate beak, laterally compressed, ventrally well raised and evident keeled, dorsally superficially sulcate, laterally slightly convex with the faces obtuse or somewhat rounded, the valves thin, strigose, trichomes white, papery and ochre with age, finely reticulate, septum almost complete; ovules 8–14; seeds 1.2–2.4 mm long, mitten shaped, brown to olive, occasionally purple tinted.

Distribution:— Endemic to Mexico, mainly in northern Mexico, central Chihuahua (Chihuahua and Aquiles Serdán), central-western Coahuila (Cuatrociénegas), Durango (Santiago Papasquiaro, Luis Moya and Tepehuanes), to western (Sombrerete) and central (Zacatecas) Zacatecas, Only one collection recorded in southern Mexico (Jalisco, R. McVaugh 16982 (MEXU) ( Fig. 23).

Habitat:— Rocky hillsides, thornscrub; arid and gravel plains; calcareous soils; arid thickets; arid grasslands; acacia scrublands; 1450–2100 m.

Comments:— At least sixteen other Astragalus species inhabit the same distributional areas of A. quinqueflorus , but only six of them have triquetrous sessile pods and simple trichomes ( A. goldmanii , A. hartwegii , A. nothoxys , A. nuttallianus , and A. pringlei ). Astragalus quinqueflorus is distinguished from all of them by its weak appearance, short stems, no larger than 12 cm long, linear leaflets, peduncles much larger than leaves, few flowers per cluster (1–7) coupled with their tiny flowers, none of other mentioned species have flowers as small as this species, especially the keel length (which never reaches 4 mm long).

Specimens examined:—CHIHUAHUA: 8 April 1885, Plains near Chihuahua, C. G. Pringle 234 ( NY) ; IV-1886, Hills and plains near Chihuahua, C. G. Pringle 711 ( NY, US) ; 10 March 1985, Wash near Potrero de Mapula village , at the base of the Sierra Santa Eulalia, P. F. Zika 8535 ( NY) ; 4 April 1888, Chihuahua, Wilkins s.n. ( US) ; 9 March 1997, Chihuahua, Chihuahua E. Estrada 6891 ( ANSM, CFNL, MEXU) ;? April 1887, Hills and plains near Chihuahua. Photograph of specimen only, C. G. Pringle s.n. ( MEXU) . COAHUILA: 3 September 1941, I.M. Johnston ( TEX-LL) . DURANGO: 25 March 5 April 1906, At Tepehuanes, E. Palmer 25 ( JEPS, NY) ; 10 November 1963, Luis Moya, H. D. Ripley 13507, R. C. Barneby ( NY, US) ; 19 March 1983, 3–5 km al Oeste de La Soledad , 11 km NW Santiago Papasquiaro, R. C. Díaz 113 ( NY) ; 30 May 1981, Hidalgo— B. Urías, J. G. Ochoa 8 ( MEXU) . HIDALGO: 20 November 1976, extremo NW de la Ciudad de Pachuca (barrio Las Peñitas), M. Medina 1812 ( ENCB) . JALISCO: 15 August 1958, R. McVaugh 16982 ( MEXU) . SAN LUIS POTOSÍ: 21 September 1973, 3 km. al Este de Sta. Efigenia , J. Villa V. s.n. ( MEXU) , ZACATECAS: VIII-1903, Zacatecas, C. A. Purpus 136 ( JEPS, US) ; 8 November 1963, El Calabazal, H. D. Ripley 13475, R. C. Barneby ( NY) ; 8 November 1963, 2 miles e. of Sombrerete, H. D. Ripley 13458 ( NY) .