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Laticíferos articulados anastomosados: novos registros para Apocynaceae

DOI: 10.1590/S0100-84042006000100012

Keywords: anatomy, apocynaceae, articulated laticifers, distribution, ontogeny.

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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.


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