| Sumario: | The genus Desmodium is represented in Santa Catarina State, Brazil, by 13 species, all with lomentaceous fruits. Shape, size and isthmus margin of loments vary, while the surface is glabrous, or covered by trichomes of different types. Morphological diversity of trichomes becomes particularly relevant to taxonomic description. The trichome types present on the surface of Desmodium fruits provide data for the identification and classification of species in the State. To assess this, three fruits of each species were collected and deposited at two herbaria, HBR and FLOR, in Santa Catarina, Brazil. Some rehydrated samples were examined using light microscopy (LM); and some sections were exposed to the following histochemical reagents: Sudan III for oils and Thionine for mucilage. The structural aspects of trichomes can be classified into uni- or multicellular and may still be simple, i.e., nonglandular or glandular. Using scanning electron microscopy (SEM), five types of trichomes were identified and analyzed among the Desmodium species studied: uncinate, uniseriate, globose multicellular, globose unicellular and subulate. Characteristics, such as loment margin and article form, glabrescent or pillous indument, trichome type, with or without papillous epidermal cells and epicuticular striations, showed relevant diagnostic value. An identification key was developed for Desmodium species from Santa Catarina State, Brazil, based on macro and micromorphological characters of the fruit. Daiane M. Freitas1*, Ademir Reis2, Roseli L. da Costa Bortoluzzi3 and Marisa Santos4Departamento de Botânica, Universidade Federal de Santa Catarina (UFSC), Campus Universitário, Florianópolis 88040-900, Brasil and Herbário Barbosa Rodrigues (HBR), Av. Coronel Marcos Konder 800, Itajaí 88301-302, Santa Catarina, Brasil; martinsf.daiane@gmail.comHerbário Barbosa Rodrigues (HBR), Av. Coronel Marcos Konder 800, Itajaí 88301-302, Santa Catarina, Brasil; ademir.reis.ufsc@gmail.comCentro de Ciências Agrárias, Departamento de Engenharia Florestal, Universidade do Estado de Santa Catarina (CAV - UDESC), Lages 88520-000, Santa Catarina, Brasil; rosebortoluzzi@gmail.comDepartamento de Botânica, Universidade Federal de Santa Catarina (UFSC), Campus Universitário, Florianópolis 88040-900, Brasil; marisa.santos@ufsc.br* Correspondence
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