Autor: Fric

Genus honouring Alvaro Obregon (1880-1928), leader of the Mexican revolution, and first president of the country, who was murdered on July 17th, 1928 during a banquet while celebrating his re-election (see portrait above, public domain).
A genus of small, subglobose to flattened, usually solitary, low growing plants, with the apex very woolly and a large taproot. Ribs absent, large angular tubercles arranged in a spiral, wide at their base, smooth, sharp, areoles located at the top of tubercles. Spines short, few (0-5), flexible, becoming deciduous. Flowers diurnal, self-sterile, funnel-shaped, appearing at the apex, creamy white, pollinated by bees. Fruits davate, at first fleshy, drying when mature, naked, indehiscent. Seeds pear-shaped, tuberculate, shiny, black. Dispersal probably ensured by ants.
The monotypic genus Obregonia grows endemically in an extremely limited area of Tamaulipas state in Mexico, on rocky or clayey areas, alluvial plains, in a xerophilous forest of dense bushes, among dead leaves, almost always in the shade, rarely in full sun (unless loss of its nurse plant), from 800 m up to 1300 m in altitude. When it rains, the erosion contributes to the destruction of many plants situated in drainage areas. It is usually found together with Agave lechuguilla, Ariocarpus trigonus, Astrophytum myriostigma, Coryphantha palmeri, Echinocereus blanckii,
Mammiilaria baumii, Neolloydia conoidea, among other cacti and succulents.
Vlexico (Tamaulipas).

Currently only one recognised species:
– Obregonia denegrii* Fric 1925

References: "TAXONOMY of the CACTACEAE" -  ISBN 978-84-617-3692-8 (Vol. 2)