EPOW - Ecology Picture of the Week

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Mammillaria of the Sonoran

Credit & Copyright:  Dr. Bruce G. Marcot
  

Explanation:  Watch where you sit!   No, these aren't golf balls sitting in the desert sun.  These are globular cacti of genus Mammillaria, so named for their mammary-gland appearance.   We are in the Sonoran Desert of southern Arizona, a bit north of Tucson outside of the town of Oracle.   More commonly called pincoushin cactus, several species of Mammillaria grow in this region.  This week's star might be Mammillaria grahamii, although it doesn't seem to sport the obvious central fishhook spines associated with this species.   The wonderful geometric design of the radiating spines resembles a regular polyhedron, where each face has five edges, thus forming a dodecahedron, although there seem to be more than 12 faces.  But I was not about to handle these specimens to count them all ...     The blooms of pincushion cacti are truly striking.