Laticifer presence is universal in Apocynaceae, in the classic literature the type described for this family is the non-articulated. Later researches have proved the occurrence of articulated laticifers only in four species, giving rise to controversies on their origin. The results obtained in our studies differ from those reported for most species of this family. In both Aspidosperma australe Müll. Arg. (Rauvolfioideae) and Blepharodon bicuspidatum Fourn. (Asclepiadoideae), the laticifers are of the articulated anastomosing type because they are formed by adding cells with rapidly dissolving transverse walls. Laticifers originate from ground meristem and/or procambium and form a branched system, they are in secretory phase since the early stages of formation in different organs, releasing latex only when the plant is damaged. The laticifer walls are exclusively pectic-cellulosic and their chemical characteristics probably change during their development. Vegetative organ laticifers occur in all stem and leaf tissues, except epidermis and medullary parenchyma of A. australe. In the flower, laticifers are found in all floral organs, except in the medullary parenchyma of the pedicel of A. australe and in the ovules of both species. The presence of the same type of laticifer in these two genera, which represent the most divergent subfamilies within the Apocynaceae corroborates the current circumscription of this family. The latex has protective function, allowing the species of this family to succeed in different environments.291133144Appezzato-Da-Glória, B., Estelita, M.E.M., Laticifers systems in Mandevilla illustris and M. velutina Apocynaceae (1997) Acta Societatis Botanicorum Poloniae, 66, pp. 301-306Backhaus, R.A., Walsh, S., The ontogeny of rubber formation in guayule, Parthenium argentatum Gray (1983) Botanical Gazette, 144, pp. 391-400Blaser, H.W., Anatomy of Cryptostegia grandiflora with special reference to the latex system (1945) American Journal of Botany, 32, pp. 135-141Christiano, J.C.S., (2002) Respostas Cecidogênicas No Modelo Aspidosperma australe (Apocynaceae) - Pseudophacopteron sp. (Homoptera: Phacopteronidae), , Dissertação de mestrado, Universidade de São Paulo, São PauloClark, G., (1973) Staining Procedures, , The Williams & Wilkins Co., BaltimoreDussourd, D.E., Eisner, T., Vein-cutting behavior: Insect counterploy to the latex defense of plants (1987) Science, 237, pp. 898-901Endress, M.E., Bruyns, P.V., A Revised Classification of Apocynaceae s.l. (2000) The Botanical Review, 66, pp. 1-56Fahn, A., (1979) Secretory Tissues in Plants, , Academic Press Inc., LondonFahn, A., (1990) Plant Anatomy, , Pergamon Press, OxfordFarrell, B.D., Dussourd, D.E., Mitter, C., Escalation of plant defense: Do latex/resin canals spur plant diversification? (1991) American Naturalist, 138, pp. 881-900Fineran, B.A., Condon, J.M., Ingerfeld, M., An impregnated suberized wall layer in laticifers of the Convolvulaceae and its resemblance to that in walls of oil cells (1988) Protoplasma, 147, pp. 42-54Gerlach, D., (1969) Botanische Mikrotechnik: Eine Einführung, , Georg Thieme, StuttgartInamdar, J.A., Murugan, V., Subramanian, R.B., Ultrastructure of non-articulated laticifers in Allamanda violacea (1988) Annals of Botany, 62, pp. 583-588Johansen, D.A., (1940) Plant Microtechnique, , McGraw-Hill, New YorkJudd, W.S., Campbell, C.S., Kellogg, E.A., Stevens, P.S., (2002) Plant Systematics: A Phylogenetic Approach, , Sinauer Associates, SunderlandLewinsohn, T.M., The geographical distribution of plant latex (1991) Chemoecology, 2, pp. 64-68Mahlberg, P.G., Embriogeny and histogenesis in Nerium oleander L.: II. Origin and development of the non-articulated laticifers (1961) American Journal of Botany, 48, pp. 90-99Mahlberg, P.G., Laticifers: An historical perspective (1993) The Botanical Review, 59, pp. 1-23Mahlberg, P.G., Davis, D.G., Galitz, D.S., Manners, G.D., Laticifers and the classification of Euphorbia: The chemotaxonomy of Euphorbia esula L. (1987) Botanical Journal of the Linnean Society, 94, pp. 165-180Marcondes-Ferreira, W., Kinoshita, L.S., Uma nova divisão infragenérica para Aspidosperma Mart. (Apocynaceae) (1996) Revista Brasileira de Botânica, 19, pp. 203-214Metcalfe, C.R., Distribution of latex in the plant kingdom (1967) Economic Botany, 21, pp. 115-127Metcalfe, C.R., Chalk, L., (1950) Anatomy of the Dicotyledons: Leaves, Stem and Wood in Relation to Taxonomy with Notes on Economic Uses, 2. , Claredon Press, OxfordMilanez, F.R., Nota prévia sobre os laticíferos de Hevea brasiliensis (1946) Arquivos Do Serviço Florestal, 2, pp. 39-65Milanez, F.R., Contribuição ao conhecimento anatômico de Cryptostegia grandiflora - II. Sobre os laticíferos da estrutura primária (Asclepiaceae) (1960) Rodriguésia, 35-36, pp. 99-128Milanez, F.R., Contribuição ao conhecimento anatômico de Cryptostegia grandiflora - III. Nota sobre a estrutura secundária (1966) Rodriguésia, 25, pp. 335-350Milanez, F.R., Ontogênese dos laticíferos contínuos de Neridium (Nerium) oleander L. (1977) Trabalhos Do XXVI Congresso Nacional de Botânica, 1975, pp. 343-379. , Rio de JaneiroMurugan, V., Inamdar, J.A., Studies in the laticifers of Vallaris solanacea (Roth) O. Ktze (1987) Phytomorphology, 37, pp. 209-214Murugan, V., Inamdar, J.A., Organographic distribution, structure and ontogeny of laticifers in Plumeria alba Linn (1987) Proceedings of the Indian Academy of Sciences (Plant Sciences), 97, pp. 25-31Pearse, A.G.E., (1985) Histochemistry Theoretical and Applied, 2. , C. Livingstone, EdinburghRoy, A.T., De, D.N., Studies on differentiation of laticifers through light and electron microscopy in Calotropis gigantea (Linn.) R. Br. (1992) Annals of Botany, 70, pp. 443-449Sacchetti, G., Ballero, M., Serafini, M., Romagnoli, C., Bruni, A., Poli, F., Laticifer tissue distribution and alkaloid location in Vinca sardoa (Stearn) Pign. (Apocynaceae), an endemic plant of Sardinia (Italy) (1999) Phyton, 39, pp. 265-275Serpe, M.D., Muir, A.J., Keidel, A.M., Localization of cell wall polysaccharides in nonarticulated laticifers of Asclepias speciosa Torr (2001) Protoplasma, 216, pp. 215-226Smith, M.M., Mccully, M.E., A critical evaluation of the specificity of aniline blue induce fluorescence (1978) Protoplasma, 95, pp. 229-254Snyder, F.W., Growth of excised tissues from the stem of Cryptostegia grandiflora (1955) Botanical Gazette, 117, pp. 147-155Solereder, H., (1908) Systematic Anatomy of the Dicotyledons, 1-2. , Clarendon Press, OxfordValente, M.C., Carvalho, L.D'A.F., Plantas da caatinga. I - Apocynaceae. Anatomia e desenvolvimento de Aspidosperma pyrifolium Mart. var. molle Muell. Arg. - "Pereiro" (1973) Revista Brasileira de Biologia, 33, pp. 285-301Van Die, J., A comparative study of the particle fractions from Apocynaceae latices (1955) Annales Bogorienses, 2, pp. 1-124Wilson, K.J., Mahlberg, P.G., Ultrastructure of non-articulated laticifers in mature embryos and seedlings of Asclepias syriaca L. (Asclepiadaceae) (1978) American Journal of Botany, 65, pp. 98-109Wilson, K.J., Maxam, T.E., Ultrastructure of articulated laticifers in Stapelia bella (Asclepiadaceae) (1987) American Journal of Botany, 74, pp. 628-628Yoder, L.R., Mahlberg, P.G., Reactions of alkaloid and histochemical indicators in laticifers and specialized parenchyma cells of Catharanthus roseus (Apocynaceae) (1976) American Journal of Botany, 63, pp. 1167-1173