MACDONALDII Nesom, 1996
Type : Andrew McDonald 2135, collected Nuevo Léon, Mpio Galeana, Sierra La Marta, S and SE sides at the top, alpine and subalpine Zone, 22 Aug 1986, Mexico. (Holotype TEX).
Distribution : Mexico (Coahuila: Sierra Coahuilón, Sierra La Viga; Nuevo Léon: Cerro Potosí and Sierra La Marta); subalpine and alpine zones, 2850 - 3600 m.
Description (by U. Eggli in IHSP, 2003) :
Erect, perennial herbs with fibrous roots, 4 – 7 cm tall.
Stems mostly hidden by the leaves, surface with low papillae and square cells in lines.
Leaves semiterete, flat above with a median groove, both faces minutely striate-papillate with clearly visible cellular structure.
Flowering branch as in S. parvum.
Flowers : Petals yellow, erect, 6 – 7 mm.
Another member of the S. parvum group (Nesom & Turner 1996) and compared with S. catorce and S. papillicaulum in the protologue, and most closely related to the latter.