Experimental Hybridization of Northern Chihuahuan Desert Region Opuntia (Cactaceae)

Possible natural hybridization among 11 taxa of Opuntia sensu stricto was investigated in the northern Chihuahuan Desert region through the use of experimental hybridization. Established plants representing specific taxa growing in the Sul Ross State University Opuntia garden were used for all experiments. Reciprocal crosses were made between putative parental taxa of field-observed putative hybrids, and each experimental cross analyzed for fruit and seed set. For each taxon, tests were performed to control for possible apomictic, autogamous, and geitonogamous seed set. Several experimental crosses were found to set seed in amounts expected for natural pollination events. Data gathered from the tests also provided basic information regarding the breeding systems of the taxa investigated. Data presented here provide support for several hypothesized hybridization events among Opuntia