Leuchtenbergia principis Origin and Habitat: North-central Mexic, where it occurs throughout much of the semi desert in the states of Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas, and Zacatecas. Although occurring over a rather large area, these cacti are sparsely scattered and can be difficult to localize. This species is uncommon. The population size is estimated to be more than 500,000 individuals.
Altitude range: It is found from 1,500 to 2,000 metres above sea level.
Habitat and Ecology: This species is found in semi desert on calcareous soil. Usually the plants occur singly, often growing in clumps of Agave or Hechtia. This species is threatened by illegal collection and cattle and goat grazing in its habitat. This species is legally protected in Mexico under the national list of species at risk of extinction, NOM-059-SEMARNAT-2010, where it is listed as “threatened” (A; SEMARNAT 2010).
Leuchtenbergia principis Description: Leuchtenbergia principis is the sole species of the genus Leuchtenbergia, it is a unique looking cactus with very long tubercles, making the plant resemble an agave. It is slow-growing but can eventually grow up to 70 cm high.
Root: It has a large, tuberous taproot.
Stem: Solitary or slowly offsetting, cylindrical which becomes bare and corky at the base with age, forming a 7.5 cm thick trunk.
Tubercles: Long, slender, grayish-green to bluish-green, triangular in cross-section, resembling triangular agave-like leaves with the tips cut off, 6-15 cm long, with purplish-red blotches at their tips. Old, basal tubercles dry up and fall off.
Areole: At the tip of the tubercle with grey wool.
Spines: The tubercles are topped with papery, flexible spines; central spines 1-2, up to 20 (or more)cm long; radials 8 to 14, up to 5(-10) cm long.
Flowers: From the areole at the tip of the new tubercles on mature plant (at least 4-5 years old)large, funnel-shaped, fragrant, yellow, 5-10 cm wide.
Fruit: Green to violet, 3 cm long and 2 cm broad, more or less glaucous, smooth. When ripe the bottom of the fruit open and release several hundred large seeds.
Blooming season: Leuchtenbergia (like the Astrophytums) flowers intermittently throughout the warm months from spring to autumn.