THE HYBRID ORIGIN OF X EPINICEREUS-COOPERI (CACTACEAE) REFUTED USING GEL BLOT HYBRIDIZATION OF RANDOM AMPLIFIED POLYMORPHIC DNAS

The phylogeny of xEpinicereus cooperi (= xSeleniphyllum cooperi, = Epi phyllum cooperi) (Cactaceae) was disputed until the reported recreatio n of the taxon through hybridization greatly bolstered the proposed hy brid origin of this cactus. The question has now been re-examined usin g molecular biological techniques. The specimens used included the ori ginal clone of xEpinicereus cooperi, a plant of the modern remake of t his reputed cross, the two reputed parent species (Selenicereus grandi florus and Epiphyllum crenatum), and plants of other Selenicereus and Epiphyllum species. Genetic comparison was performed using Random Ampl ified Polymorphic DNAs(RAPDs). Potential artifacts of this technique w ere overcome by applying gel blot hybridizations to the RAPD patterns. Pairwise comparisons of RAPD patterns of specimens were made by calcu lating Dice Similarity Coefficients. Analysis strongly indicates that xE. cooperi is not of hybrid origin; there is no evidence that Selenic ereus is in its ancestry. As there are no other reputed instances of S elenicereus being crossed with Epiphyllum, the hybrid genus xEpinicere us (and its later synonym, xSeleniphyllum) are to be considered superf luous. Epiphyllum cooperi differs from Epiphyllum crenatum var. kimnac hii only in having the outer tepals attached to the apex of the recept acle, rather than extending further down the tube. Applying taxonomic standards currently used for the Cactaceae, it seems best classified a s a horticultural selection, Epiphyllum crenatum var, kimnachii 'Coope ri'.