Origin of thickening in monocotyledon stems, slope variation and population structure in a riparian forest, and the influence of seagrass beds in fish community structure.

Among the interesting studies published in this issue of the AABC that should be highlighted is the work on the primary and secondary thickening in the stem of a monocotyledon species by Marina B. Cattai and Nanuza L. de Menezes from the Instituto de Biociências of the Universidade de São Paulo. There is still great discussion over how this thickening occurs in this major group of flowering plants. The debate on this subject started in the nineteenth century and is nowadays centered in the notion of a “primary thickening meristem” (PTM, for a review see Rudall 1991). Addressing this question, Cattai and Menezes (2010) determined how primary growth takes place in Cordyline fruticosa, also popularly known as cabbage palm, and how it affects the secondary thickening meristem. The authors have essentially based their study on histological cross-sections of specimens original from Asia, collected from the garden of the Instituto de Biociências.