Brazilian Journal of Botany
On-line version ISSN 1806-9959
DEMARCO, Diego and CASTRO, Marilia de Moraes. Articulated anastomosing laticifers in species of Asclepiadeae (Asclepiadoideae, Apocynaceae) and their ecological significance. Rev. bras. Bot. [online]. 2008, vol.31, n.4, pp. 701-713. ISSN 1806-9959. http://dx.doi.org/10.1590/S0100-84042008000400015.
Laticifers occur in all members of Apocynaceae. They are described as nonarticulated branched by most authors, but articulated laticifers have been reported to some species of this family. The present study aims to describe the laticifer ontogeny, structure, distribution, and type in vegetative organs of Fischeria stellata (Vell.) E.Fourn., Gonioanthela axillaris (Vell.) Fontella & E.A. Schwarz, Matelea denticulata (Vahl) Fontella & E.A. Schwarz, and Oxypetalum banksii Schult. and re-evaluate the laticifers of Asclepias curassavica L. from Atlantic rainforest, comparing the results with those of species from "cerrado" vegetation. The laticifers of these five species are articulated anastomosing, whose transverse or oblique walls dissolve rapidly and entirely. The laticifers branch through lateral anastomoses and form a continuous system throughout the adult plant. They are observed in primary tissues of stem and leaf, except in epidermis; they are also present in the secondary vascular tissue, except in the secondary xylem of A. curassavica. The ontogeny of these laticifers may explain the divergence between our data and those recorded for most species of the family. The results obtained revealed that the ontogeny, type, structure, and distribution of laticifers of the species of Asclepiadeae from "restinga", lowland humid forests, and "cerrado" vegetation are similar. The continuity of the articulated anastomosing laticifer system ensures a greater latex flow into the injured organ, releasing the laticifer exsudate simultaneously, coagulating and sealing the wounds rapidly, besides hindering the entrance of microorganisms.
Keywords : articulated laticifers; Asclepiadeae; ontogeny; restinga; lowland humid forests; structure.