A structural study on the foliar colleters of Prestonia coalita (Vell.) Woodson was conducted in order to establish their number and positions, to describe their structure, to determine in which stage of leaf development secretion starts and to comprove the presence of mucilage in its secretion. Each node presented 14-18 intrapetiolar colleters, whose differentiation occurs in the early stages of leaf development, and secretion occurs in leaf primordia with 5-8 mm length. Colleters are constituted by a long head that includes a central core of parenchymatous cells, surrounded by one layered palisade secretory epidermal cells, and a short stalk devoid of any epidermal secretory cells. Multicellular hairs and vascular tissue were observed only in intermediary colleters, which correspond with modified stipules.These structures' identification as colleters is confirmed by the presence of mucilage in secretion. The stipular nature of most colleters is confirmed, while only central colleters are originated from leaf axil.
Colleters; leaves; secretion; Prestonia coalita; Apocynaceae
