Structural, functional and phylogenetic aspects of the colleter
1991
Tōmas, Vi.
This article surveys the structural, functional and phylogenetic significance of colleters in different dicotyledonous families. Colleters are multicellular secretory structures attached to the stipule, petiole, lamina, bract, bracteole, calyx and corolla. Colleters are grouped into standard (S), dendroid (D) and brush-like (B) types on the basis of their morphology and structure. D and B-type colleters occur in certain members of Rubiaceae that also have bacterial leaf nodules. Besides the normal structure, epithelial hairs, thin-walled subepidermal cells, laticifers and vasculature are present in many colleters of Apocynaceae. It is probable that the colleter functions to protect the developing meristem by secreting a viscous fluid. Exudate of D-type colleters are mucilaginous, providing the substrate necessary for the nutrition of endophytic bacteria.
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