artichoke cactus

Obregonia denegrii typically grows as a single plant, characterized by a sunken and woolly apex. This rare species resembles an inverted green pine cone with a woolly center. The stems take on a globular-squashed form with a woolly center, reaching diameters of up to 15 cm (5.9 in) and showcasing a color spectrum from greyish green to dark green. Small areoles are situated at the tips of the tubercles, adorned with wool in their early stages. The areoles exhibit 2 to 4 whitish to brown spines, measuring approximately 5 to 15 mm (0.20 to 0.59 in) in length, on the young tubercles. These spines are soft, flexible, slightly curved, and tend to shed rapidly. In the summer, flowers bloom, emerging between the wool of the apex and at the center of the stem on young tubercles. These flowers take on a funnel-shaped, diurnal, white appearance, with dimensions reaching up to 2.5 cm (0.98 in) in diameter and 2.5-3 cm (1.2 in) in length. The external perianth segments exhibit a greyish hue, and the pericarpel is either exposed or possesses a few scales. Filaments are reddish-purple or pink, anthers are yellow, and both the style and stigma lobes are white.

Obregonia denegrii originates from the Valley of Jaumave in Ciudad Victoria, Tamaulipas, Mexico, commonly thriving at elevations around 1000 meters. This plant prospers in semi-desert open areas and dense bushes. It grows slowly in culture and requires little water. It benefits from full sun and is multiplied by seed. It is very slow growing. It is assessed as endangered on the IUCN Red List .

The Nahuatl Indians call the plant peyotl, and it is said to have hallucinogenic alkaloids. It is one of the closest living relatives of the genus Lophophora.