Psychotria carthagenensis (Rubiaceae) is identified by the presence of lanceolate apical stipules. Several Rubiaceae genera have stipules with secretory structures called colleters. Little is known about the structures of stipules and colleters. This work aimed to characterize anatomically the stipules and the colleters of Psychotria carthagenensis from Santa Catarina state (Brazil). Apical shoot stipule samples were collected, fixed, and processed for light and scanning electron microscopy studies. Histochemical tests were made on in vivo material. The bases of stipules are connected and the apices are separate. On the adaxial surface, there are multicellular trichomes and the colleters are found among these. They have a constricted base, pores on the cuticle surface, parenchymatic middle axis surrounded by a layer of palisade-like epidermal cells, in which may have raphides. The colleters secrete a mucilaginous substance that is very important to protect the apical shoot and young leaves.
colleters; stipules; Psychotria carthagenensis; Rubiaceae
