Atributos estruturais e histoquímicos das glândulas cróceas de Polygala adenophora Dc. (Polygalaceae).

Abstract

Croceous glands are visible structures defined by their rounded shape and yellowish color. They have great taxonomic importance, being used to delimit the Timutua section, one of the 14 sections of the subgenera Polygala, belonging to the genera Polygala L., the most representative of the family Polygalaceae, with about 120 species recorded for Brazil. However, croceous glands still lack more complete information about their nature. Thus, the present study aims to investigate the origin, structure and function of the croceous glands existing in the floral structures, fruit, leaf blades and stem of Polygala adenophora DC. Samples of flowers, fruit, leaf blades and stem of P. adenophora DC. at different stages of development (flower buds, fully developed flowers and fruits; stem and leaf samples were taken from the 1st, 3rd, 6th and 9th nodes), that went obtained from field collection. Collected samples were fixed in FAA50 (formaldehyde, glacial acetic acid and 50% ethyl alcohol) or FNT (buffered neutral formalin) and submitted to standard techniques in light microscopy and scanning electron microscopy. Histochemical tests were carried out for lipophilic and hydrophilic substances. The results show that the croceous glands are secretory cavities, present formation of schizogenous origin, being found since the beginning of the development of vegetative and reproductive organs. The cavities secrete a substance of an exclusively lipophilic nature, composed of essential oils and lipids, this exudate possibly presents a protective function, acting in the defense against attacks and herbivory.