Comparative anatomy of calyx and foliar glands of Banisteriopsis C. B. Rob. (Malpighiaceae)

Abstract

Banisteriopsis is considered one of the largest genera of Malpighiaceae with 58 species, of which 47 occur in Brazil. The typical calyx and leaf glands of Banisteriopsis are considered relevant to the adaptive success of Malpighiaceae. Comparative studies of anatomical and histochemical characteristics may reveal similarities and assist in the interpretation of the functions performed by such glands. The present study aimed to describe the anatomy of the calyx and leaf glands of 38 species of Banisteriopsis that occur in Brazil, and to analyze these structures histochemically in B. campestris, B. laevifolia and B malifolia, using standard methods. Calyx glands differ from leaf glands by possessing an irregular surface that is covered by a thick cuticle that is released from the epidermis by the accumulation of secretion; the glands are similar in all the other anatomical characteristics. Both types of glands produce secretions composed of a mixture of protein granules, lipids and polysaccharides. These findings reinforce the hypothesis that foliar glands have given rise to calyx glands in response to interactions with pollinators.

Leaf glands of Banisteriopsis muricata (Malpighiaceae): distribution, secretion composition, anatomy and relationship to visitors

“…The nectariferous parenchyma of the EFNs of B. muricata is similar to that observed in other species of the genus Banisteriopsis (Araújo & Meira 2016) and other genera of the family Malpighiaceae, such as Peixotoa (Machado et al 2008) and Diplopterys (Possobom et al 2010). Dense cytoplasm and conspicuous nuclei are cytological features of the nectariferous parenchyma cells of B. muricata, and secretory cells in general, indicating high tissue metabolic activity (Fahn 1979).…”

“…These glands are cup-shaped with a short peduncle, a discoidal apical portion and a slightly concave secretory surface, which characterize them as "high type" according to the classification of Elias (1983). Similar morphology has been observed in the leaf glands of other species of Banisteriopsis (Machado et al 2008;Araújo & Meira 2016), but in yet others the leaf glands are sessile (Machado et al 2008). The leaf glands of Banisteriopsis muricata possess a secretory surface that is restricted to the central region of the gland, which is common in some species of Banisteriopsis (Araújo & Meira 2016) and Galphimia brasiliensis (Castro et al 2001), but not in other Malpighiaceae, such as Peixotoa reticulata (Machado et al 2008).…”

“…The EFNs of B. muricata consist of secretory epidermis, nectariferous parenchyma and vascularized subnectariferous parenchyma, as is typical for EFNs of species of Malpighiaceae (Machado et al 2008;Possobom et al 2010;Araújo & Meira 2016). The accumulation of secretion in the subcuticular spaces and the absence of stomata, or any other type of opening to release the secretion of EFNs of B. muricata, suggest that the elimination of nectar occurs gradually via permeability of the cuticle or by its rupture after foraging by ants.…”

“…Extrafloral nectaries may be vascularized by xylem and phloem (Fahn 1979;Elias 1983), as in B. muricata and other species of Malpighiaceae (Machado et al 2008;Possobom et al 2010;Araújo & Meira 2016), but they may also possess only one type of vascular tissue or no vascular tissues at all (Fahn 1979;Paiva et al 2007). The amount of vascular tissue in nectaries is considered proportional to their size (Carlquist 1969) and to the volume of secretion produced (Paiva et al 2007).…”

“…Despite the great morphological diversity and the associated taxonomic and ecological value assigned to leaf glands in Malpighiaceae (Elias 1983), anatomical studies have been restricted to certain genera such as Banisteriopsis (Araújo & Meira 2016), Heteropteris, Peixotoa (Machado et al 2008), Galphimia (Castro et al 2001) and Diplopterys (Possobom et al 2010). Moreover, aspects of the ontogenetic development of these leaf glands are unknown.…”