Floral colleters in Pleurothallidinae (Epidendroideae: Orchidaceae)

• DOI: 10.3732/ajb.1400012
• Publication Date: 2014-04-01T05:58:08Z
• Authors: Poliana Cardoso‐G...; Lisa M. Campbell; Solange C. Mazzon...; and Fábio de Barros
• Keywords: Trichome; Orchidaceae; Exudate; Subfamily

• Premise of the study: The term colleter is applied to trichomes or emergences positioned close developing vegetative and floral meristems that secrete a sticky, mucilaginous, and/or lipophilic exudate. Several ecological functions are attributed these glands, but none exclusive colleters. Patterns morphology distribution colleters may be valuable for systematics phylogeny, especially concerning problematic large groups such as subtribe Pleurothallidinae, also essential understand evolution glands in Orchidaceae whole. Methods: We used scanning electron light microscopy examine structure occurrence on bracts sepals invaginations external ovary wall (IEOW) flowers several developmental stages from species seven genera. Key results: exudate was composed polysaccharides, lipophilic, phenolic compounds. Colleters were secretory only during development organs, except IEOW active at anthesis. After phase, fungal hyphae found penetrating senescent trichomes. Conclusions: Trichome‐like seem widespread character Epidendroideae, digitiform possibly common type this subfamily. Mucilage aid establishment symbiotic fungi necessary seed germination. presence case homeoheterotopy, which extrafloral nectaries produce simple sugar‐based secretions (as other orchid species) have changed with complex Pleurothallidinae.