Star cactus occurs in the Rio Grande Valley of South Texas (Starr and Zapata counties, historically in Hidalgo, and reported from Cameron County although no habitat exists there). The cactus also grows in northern Mexico in Coahuila, Nuevo Leon, and Tamaulipas.
In the wild, star cactus is a flat, or at most, dome-shaped, spineless cactus to 15 cm in diameter. The green or dark-green to brownish green stems are divided into eight triangular sections. Each section has a row of small, white tufts of hairs down its middle. Generally, the stems are also dotted with scattered white specks. Star cactus flowers are yellow with a red to orange center (3-5 cm in diameter). The green, woolly fruits are oval (15-20 mm long, 12 mm wide) and turn brown-red at maturity.
Star cactus can be confused with peyote (Lophophora williamsii). The stems of peyote are bluish-green, can have 5-13 variously shaped sections, and have no white specks. Peyote also has pink flowers that are smaller (≤2 cm across) than star cactus flowers.
Star cactus grows on gravelly, somewhat salty, clay or loam soils in areas of sparse vegetation in grassy thornscrub.
Life Cycle Events
Star cactus flowers March through May and occasionally after high rainfall; fruiting follows from April to June.
Star cactus can be identified all year round; however, it is most visible while in flower March to May. During extreme drought, the plants may sink below the ground surface, becoming extremely cryptic and difficult to find.
- Rare Plants of Texas
- U.S. Fish and Wildlife Service
- Flora of North America
- Janssen, G.K., J.M Poole, and P.S. Williamson. 2010. The research and recovery of star cactus (Astrophytum asterias). Section 6 final report. Austin: Texas Parks & Wildlife Department.
- Westlund, B.L. 1991. Cactus trade and collection impact study. Section 6 final report. Austin: Texas Parks & Wildlife Department.