Astragalus piscinus (M. E. Jones) Barneby, Shreve & Wiggins, Veg. Fl. Sonoran Des.

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

71. Astragalus piscinus (M. E. Jones) Barneby, Shreve & Wiggins, Veg. Fl. Sonoran Des. 1: 703. 1964

Type: — MEXICO, Baja California, Lagoon Head , 6–15 March 1889, Plamer 776 (holotype: US 00001503 digital image!: isotype: MEXU 01169237!, GH 00059428 digital image!) .

Astragalus douglasii (Torr. & A. Gray) var. piscinus M. E. Jones, Contrib. West. Bot. 10: 61. 1902. — Astragalus crotalariae Torr. var. piscinus (M. E. Jones) Jeps., Fl. Calif. 2: 350. 1936.

Perennial. Stems up to 35 cm long, basally hollow, striate, minute strigose, trichomes up to 0.8 mm long, appressed, sub-appressed or straight. Stipules 3–5.3 mm long, lanceolate to ovate, semi-clasping, decurrent, not connate. Leaves 6–14.5 cm long, leaflets 15–25, 4–33 mm long, linear, wide-oblong, elliptic to narrow oblanceolate obtuse or/and mucronate, adaxially glabrate; Peduncles 11.2–15.5 cm long, striate; the racemes 2–5.5 cm long, flowers 6–22. Flowers ascendant, purple; the calyx 4.9–5.1 x 3 mm, strigose, the trichomes white o white and black mixed, the tube 3.5 mm long, campanulate, the teeth 1.5–1.6 mm long, subulate; the banner 1–1.3 × 0.6–0.7 cm, recurved, ovate to rhombic, basally narrow, apically retuse; the wings 9.2–11.6 × 2–2.4 mm, the claw 4–4.9 mm long, the blade 5.6–7.5 mm long, oblanceolate to oblong, oblique; the keel 8.4–9.2 × 2.3–2.6 mm, the claw 4–4.8 mm long, the blade 4.6–5.1 mm long, semi-elliptic, lunate. Pod 2–3 × 1–1.2 cm, ascendant o spreading, sessile (or with a minute gynophore soon and easily caducous), obliquely-elliptic, inflated, bladder-like, basally rounded to sub-conic, distally contracted in a triangular, straight to incurved triangular beak, 5–7.3 mm long, ventral suture slightly sulcate, dorsally strongly convex, the valves papery, minute strigose, ochre y transluscent, septum absent; ovules 18–25; seeds 1.5–1.9 mm long, mitten shaped, brown and opaque.

Distribution:— Endemic to Mexico, exclusively from Baja California, at the border with Baja California Sur ( Fig. 21 ).

Habitat:— Desert plains; roads adjacent to the bay; gravel soils, 25–350 m, it occurs only on a very specific substrate on a small cerro near the ocean to the west of Jesus Maria. This is north of Guerrero Negro and in the extreme southern part of the state of Baja California. Common on sandy soils of this coastal cerro, but occured nowhere else. According to Rebman,..”I am pretty sure it is a micro-endemic species due to the specialize substrate at this locale (sic).

Comments:— The western coasts on the geopolitical boundaries of Baja California Sur, at the height of Turtle Bay and Guerrero Negro harbor three species of Astragalus with purple or white flowers but with lilac tones, inflated, sessile and bladder-like pods, A. magdalenae (2 varieties), A. hornii var. minutiflorus and A. piscinus . Astragalus magdalenae can be distinguished by its silvery and shiny leaden pubescence, the calyx teeth 1.8–2.7 mm long; the other two species has green to green-cinerose stems, calyx teeth shorter, 1.5–1.7 mm long and shorter keel, 3–4.8 mm long; A. hornii var. minutiflorus is distinguished of A. piscinus by its shorter (9–17 mm long) pod, holding 11–17 ovules.

Specimens examined:— BAJA CALIFORNIA: 21 April 2017, West of Villa Jesus Maria and Mex Hwy 1; near Laguna Manuela; on Morro de Santo Domingo ; along the road to the lighthouse, J. Rebman 33081, J. LaGrange, D. Applegate, F. Escoto R., M. Rodríguez E. ( SD) ; 21 April 2017, West of Villa Jesus Maria and Mex Hwy 1; near Laguna Manuela; on Morro de Santo Domingo ; along the road to the north of the lighthouse, J. Rebman 33087, J. LaGrange, D. Applegate, F. Escoto R., M. Rodríguez E. ( SD) .

Figures

FIGURE 21. Map showing the distribution of Astragalus palmeri, A. parvus, A. pennellianus, A. pilosior, and A. piscinus in Mexico.