INTERSPECIFIC HYBRIDIZATION BETWEEN BANKSIA-HOOKERIANA MEISN AND BANKSIA PRIONOTES LINDL (PROTEACEAE)

Interspecific hybridization oi Banksia hookeriana and Banksia prionote s was investigated via pollen tube growth. seed set, morphological mea surements, and analysis of RAPD polymorphisms. Pollen tube growth to t he ovary was observed following selfing and crossing pollination oi ea ch species and following interspecific hybridization to B. hookeriana as the female parent, but not in the reciprocal cross. All crosses res ulted in seed set, except for self-pollination of B. prionotes and int erspecific pollination to B. prionotes as the female parent. Mortality of hybrid seedlings was high. RAPD analysis of hybrid seedlings from two families showed paternal B. prionotes bands in all 11 tested seedl ings, Leaf length or width of nine hybrid seedlings that survived to t he 10-leaf stage was intermediate between that of intraspecific seedli ngs of both parents at the same age. A mature natural interspecific hy brid was fertile following controlled selfing and backcrossing to each parental species, as well as following open pollination, but seed set was lower than for the parental species. It was concluded that hybrid ization between B. hookeriana and B. prionotes is unilateral, with int erspecific seed set of B. hookeriana comparable to that following intr aspecific pollination.