HYBRIDIZATION AND INTROGRESSION IN CARPOBROTUS SPP (AIZOACEAE) IN CALIFORNIA .1. MORPHOLOGICAL EVIDENCE

Individuals of the invasive non-native plant species Carpobrotus eduli s, its native or naturalized congener C, chilensis, and putative hybri ds are found throughout coastal California. This study characterized m orphological variation within the genus and assessed the extent of hyb ridization and direction of introgression between C. edulis and C, chi lensis. Twelve randomly selected Carpobrotus individuals from each of 49 sample locations were classified as ''C. edulis ''C. ''chilensis,'' or one of three intermediate morphotype classes, and compared for clo nal, vegetative, and fruit characters. Univariate comparisons showed t hat C. edulis individuals had deeper mats with more cover within the m at boundary, longer, wider, more serrate leaves, and wider fruits with more carpels than intermediate and C. chilensis morphotype classes, C arpobrotus Edulis and intermediates had more lateral branches than did C. chilensis, suggesting that hybrids tend to vary toward C. edulis. Discriminant function analysis (DFA) identified the following characte rs as discriminating significantly among Carpobrotus groups: leaf leng th. leaf width. leaf length/width, number of lateral branches, number of carpels, and fruit diameter, Using these characters, DM correctly c lassified 98% of apparently pure C edulis and C, chilensis. but only 7 6% of all Carpobrotus individuals when putative hybrids were included. Principal components analysis showed that C. edulis and C. chilensis cluster into distinct morphotypes. but that hybrids overlap with both groups. particularly with C. edulis. The genus Carpobrotus in Californ ia resembles a large hybrid swarm, with putative hybrids forming a lar ge portion of the overall population and tending to vary toward C, edu lis.