Trichomes that secrete substances of a mixed nature in the vegetative and reproductive organs of some species of Moraceae

Abstract

Th is study aimed to obtain new information about the distribution, morphology and content of secretory trichomes present in the vegetative and reproductive organs of four species of Moraceae: Artocarpus heterophyllus, Dorstenia cayapia, Maclura tinctoria and Sorocea bonplandii. Stem, leaf, fl ower and infl orescence samples were processed for scanning electron and light microscopy. Th e species have secretory trichomes on the leaf blade, petiole and stem and also on the infl orescence and fl owers of D. cayapia and S. bonplandii and on the peduncle of the infl orescence in A. heterophyllus. Th ese trichomes are of the capitate type in all species, but A. heterophyllus also possess peltate secretory trichomes. Both trichome types exhibit a multicellular head and a unicellular peduncle. Peduncle size and head cell number varies according to species. Peltate trichomes located in depressions were found only in species of Artocarpus, and so should be of diagnostic value for the genus. In all species the trichomes secrete polysaccharides, alkaloids and lipids; phenolic compounds occur in A. heterophyllus and M. tinctoria trichomes. Th ese trichomes probably act in the protection against herbivores, pathogens, desiccation and/ or UV radiation. Moreover, the trichomes found in the infl orescence of D. cayapia may exert a function in pollen grain adhesion.

Morphoanatomical and preliminary phytochemical studies of two specimens of Dorstenia Contrajerva native to Guatemala

“…Glandular hairs with a globular 1-2 cellular head, and unicellular stalk and papillary hairs. Most of these hairs had been reported previously for members of Moraceae family, 15,16 but they were better described by Jacomassi et al 14 Elevated above epidermis hairs seen in this study were not previously reported for this genus. Also, there is no previous report of pluricellular rosette-like bases of hairs, probably because most of the studies do not include diaphanized leaf, but were previously described for other Moraceae species.…”

Floral resins of Philodendron adamantinum (Araceae): secretion, release and synchrony with pollinators

“…Other substances seem to be enrolled in adhesion of pollen, as reported by Schnetzler et al (2017) for polysaccharides in trichomes of Dorstenia cayapia (Moraceae). In oil-producing Cucurbitaceae, Possobom & Machado (2017) reported the adhesive properties of oil from male flowers, which adhere the pollen grain to the body of floral visitors.…”

A Charcoalified Ovule Adapted for Wind Dispersal and Deterring Herbivory from the Late Viséan (Carboniferous) of Scotland

“…This is even the case for very small plant organs, where there may be pressure from spider mites or other herbivores (Walters 2017). Many secretions also have dual roles (Schnetzler et al 2017) as both antiherbivore and antimicrobial (Farmer 2014). The tip of the gland could act as a physical defense but when broken, for instance, by an arthropod, could release its toxins (Walters 2017).…”