Morfo-anatomía de perigonio, gineceo y fruto en Trichocereus candicans y T. pseudocandicans (Cactaceae): implicancias taxonómicas y reproductivas.

Background and aims: Sierras de Famatina are an important area of ​​endemism, where two representatives of Trichocereus coexist, whose taxonomic identity is discussed. Trichocereus. pseudocandicans is endemic, with colorful, diurnal flowers; while, T. candicans has a wider distribution, with white and nocturnal flowers. Taking these differences into account, we carried out a morpho-anatomical study of perigonium, gynoecium and fruit, making qualitative and quantitative comparisons. The objective is to generate new information for the genus, provide reliable taxonomic traits, and make inferences about its reproductive biology. M&M: We made temporary and permanent histological preparations of flowers and fruits, using classical techniques. In addition, we analyzed 43 morpho-anatomical variables, which were statistically compared. Results: The entities present similar morpho-anatomical traits but are differentiated by the color of the perigonium and the total size of the flowers. The following characters stand out: the style presents a stilar canal and transmitter tissue, the receptacle and the ovary wall are notoriously different but intimately fused, even after fertilization, circinate ovules, among others. Only 27.9% of the variables analyzed resulted in statistically significant differences, the flowers of T. candicans being slightly larger than those of T. pseudocandicans. Conclusions: The similarity found between the taxa reaffirms their high degree of kinship, and it is possible that T. pseudocandicans is a subspecies or hybrid of T. candicans. On the other hand, the different floral traits could be due to a high phenotypic variability, influenced by the particular characteristics of the Famatina Sierras.