On the cover.Ariocarpus retusus is one of the most widely distributed, and the most variable species of the genus. Plants growing in the area of Aramberri, Mexico in the state of Nuevo Leon, have attracted special attention for even greater variability within the individual colonies. The plant illustrated on the cover (photographed by Rob Skillin in the fall of 1995) comes from a colony east of town where vegetative characteristics range from classic retusus (broad, blunt, gray-green tubercles) to forms more suggestive of trigonus (long, sharply pointed, yellow-green, incurving tubercles). Plants may or may not have an areolar pad on the tips or their tubercles. Flower color just adds to the confusion: the retusus-like plants have deep pink flowers, as pictured, not the expected white, while trigonus-like plants have white flowers with none exhibiting the expected yellow. Such mixed characteristics have led to the speculation that these colonies are natural hybrid swarms, which has contributed to the submerging of A. trigonus as a subspecies of A. retusus. |