23 September 1983.
Zacatecas, Mexico
Locality: Sierra de Sombrerete. From San Martin, near Hwy 45, 5 km along the track to the microwave tower.
Coordinates: 23.6333, -103.6500
(Map it)
Elevation: 2760m.
Environment description: Quercus, Juniperus and scrub vegetation, including dwarf oak. Plants scattered among rocks in the brown soil.