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Stipules are leaf structures common in many groups of plants that can take a variety of forms. In Gentianales, interpetiolar stipules are considered a synapomorphy of Rubiaceae but in this study we detected two lateral expansions at the base of the leaf primordia (stipules) that give rise to colleters in many genera of Apocynaceae, similarly to Rubiaceae species. Through ontogenetic study it was possible to prove for the first time that Apocynaceae is a stipulate family whose stipules are modified into colleters, and their absence might be a secondary loss, changing the interpretation of stipule evolution in Gentianales.