Astragalus sect. Rupertii, Castillón & Quintanilla & Salinas, 2022

Castillón, Eduardo Estrada, Quintanilla, José Ángel Villarreal & Salinas, Alfonso Delgado-, 2022, A new section of Astragalus (Fabaceae: Galegeae) from Mexico, Phytotaxa 545 (1), pp. 79-86 : 80-83

Astragalus sect. Rupertii sect. nov A.E. Estrada, Villarreal & A. Delgado

Type:— Astragalus rupertii Villarreal & M.A. Carranza , Brittonia 46 (4): 335–339. 1994 (designated here, Fig. 1 ).

Plants perennial, erect to ascending, the young stems and foliage densely white-villous, stipules free, the lowermost auriculate, leaflets 15–23, elliptic, elliptic–obovate to obovate, retuse. Inflorescences in racemes, peduncles 3–15 cm long, floriferous axes 2–10 cm long, pedicels recurved, 2 mm long, caducous, falling with the ripen fruit. Calyx suboblong–urceolate to subglobose–urceolate, 8–10 × 3.5 mm, densely hirtellous, the trichomes white, black or mix of both colors, the tube 3–5 mm, the teeth 3-5 mm long, subulate to triangular subulate. Petals blue to blue-violet and basally white, the banner recurved through 26° to up to 110° with age from the vertical, emarginate, the wings 12–13 mm long, half obovate, the keel 9–11 mm long, strongly incurved distally. Ovary subsessile, hirtellous. Ovules 4. Pod covered by the calyx, 6–8 × 4–6 mm, elliptic to suboblong, tumescent (inflated but no bladder-like), slightly compressed laterally and abruptly contracted at the apex, style persistent, at least the base, septum complete, the pod two–celled. Seeds 4, 2.3 × 2 mm, mitten-shaped, brown-red, smooth, shiny.

Etymology:— The name Rupertii of this new section is in honor to Rupert Charles Barneby (1911–2000), specialist and author of the monumental work of Astragalus of North America.

The next dichotomous key is added to recognize and differentiate this new section from the other ones that grouped species in Mexico (adapted from Barneby 1964, Estrada et al. 2020).

Figures

FIGURE 1. Photograph of the isotype of Astragalus rupertii, “Courtesy of the C. V. Starr Virtual Herbarium of The New York Botanical Garden (http://sweetgum.nybg.org/science/vh/).”