54. Astragalus lyonnetii Barneby, Mem. New York Bot. Gard. 13(1): 162. 1964 Type:— MEXICO, Morelos, Toro, 9000–9800 feet, 5 August 1924, G. L. Fisher 260 (holotype: US00004205 digital image!). Perennial. Stems up to 30 cm long, decumbent or suberect, strigose and pilose, the trichomes up to 0.6 mm long, appressed, subappressed or completely straight. Stipules 1–8 mm long, the lowest ones connate and amplexicual, bidentate, the upper ones connate, attached to the middle of its length or less, pubescent. Leaves 3–7 cm long, leaflets 9–27, 2–12.3 mm long, linear, oblong to oblanceolate, distally truncate o retuse, adaxially glabrate. Pedunucles 3–11 cm long, almost always with black trichomes, rarely few with ones; the racemes up to 2.5 cm long, dense, with black trichomes, flowers 11–20. Flowers ochroleucous, turning pale yellow when drying, ascending, but deflexed with age; the calyx 5.2–7.4 × 2.2–2.8 mm, pilose, with black trichomes, sometimes mixed with few white trichomes, the tube 2.9–4.4 mm long, campanulate, the teeth 2.3–3.8 mm long, subulate; the banner 10–12.5 × 4.1–5.2 mm, rhombic, elliptic to oblanceolate, slightly retuse; the wings 9.5–9.8 × 1.6–2 mm, the claw 4–4.6 mm long, the blade 6.6–7.1 mm long, linear to oblanceolate; the keel 7.7–8.7 × 2.1–2.4 mm, the claw 4–4.7 mm long, the blade 4.5–5 mm long, obovate, abruptly incurved. Pod reflexed, stipitate (stipe 2.8–3.1 mm long), the body oblong to elliptic, 10–14.3 × 3.2–3.9 mm, obtusely triquetrous, basally cuneate, distally contracted in a short, straight beak, ventrally convex, dorsally openly sulcate, the valves thin, strigose, with black trichomes, becoming papery, ochre with age, reticulate; seeds not seen. Distribution:— Endemic to Mexico; recorded around Mexico City, State of Mexico and Morelos (Fig. 16). Habitat:— In conifer forest, 2500–2700 m. Comments:— The areas around Mexico City, adjacent areas with the State of Mexico, and Morelos harbor at least 11 species of Astragalus, however only two of these have triquetrous stipitate pods, A. lyonnetii and A. micranthus var. micranthus. The later species can be distinguished by its larger racemes (10–16 cm long, rarely 3–8 cm), more flowers per raceme (30–60), smaller petals (banner 4.9–7 mm, wings 6.1–7.9 mm, the keel 4.8–7 mm) and shorter stipe (0.1–0.5 mm). In higher mountains (3000 m or more in elevation), A. harshbergeri inhabits the same areas that A. lyonnetii, but are easily distinguished by the creeping beahivor and the much wider stipules, which are double the stem´s width. There is a asample collected at Michoacán identified a A. lyonnetii (B. Farfán H. 186, IEB), however it does not have pods and the racemes have only two flowers; perhaps a misidentification. Specimens examined:—MEXICO CITY: VIII-1927, Pedregal de San Angel, E. Lyonnet 176 (NY, US); 11 July 1984, C. Nieto P., A. Colín PR.1 (IBUG, MEXU). MORELOS: 11 July 1976, Tres Cumbres, sobre la carr. Federal a Cuernavaca, A. Delgado S. 252 (MEXU); 5 June 1972, Autopista, J. Vázquez 3639 (MEXU); 1 August 1987, M. Diaz G. 11, E. Cedillo (ENCB). STATE OF MEXICO: 3 September 1967, D. E. Hernández s.n. (MEXU); 11 August 1978, R. Vega A. 381 (ENCB).

Published as part of Castillón, Eduardo Estrada, Quintanilla, José Ángel Villarreal, Delgado-Salinas, Alfonso & Rebman, Jon P., 2023, The genus Astragalus (Leguminosae: Papilionoideae: Galegeae) in Mexico, pp. 1921-1935 in Phytotaxa 586 (1) on pages 1921-1935, DOI: 10.11646/phytotaxa.586.1.1, http://zenodo.org/record/7703999