Cambios anatómicos en la corteza de Parkinsonia praecox (Ruiz et Pavón) Hawkins causados por la epífita Tillandsia recurvata L. (Bromeriaceae)

Tillandsia recurvata L. is commonly found growing on the branches and trunk of Parkinsonia praecox (Ruiz et Pavón) Hawkins in the semi-arid area of the Zapotitlán Salinas Valley, Mexico, and this relationship seems to affect the phorophyte in different ways. The purpose of this study was to evaluate the effect of the establishment of T. recurvata on bark tissues of the phorophyte P. praecox. The anatomical study of the bark allowed to recognize the presence of non-collapsed phloem, collapsed phloem, a cortex whose cells under the epidermis show chloroplasts and a multiple epidermis covered by a wide epicuticular wax layer. Tillandsia recurvata roots never penetrate the tissues. However, in those zones where the epiphyte occurs a wound periderm develops below the epidermis. Wound periderm provides protection against infection, but it probably also affects negatively the mobilization of carbon dioxide toward internal tissues or the dissipation of heat and light. These aspects seem to be more important than the photosynthesis decrease in branches where the epiphyte establishes. It is likely that the overweight caused by the large number of Tillandsia recurvata individuals on the branches prevents the adequate architectural development of the phorophyte Parkinsonia praecox.