A comparative study of the secondary xylem (wood) anatomy of 11 species (38 specimens) occurring in cerrado s.s. and the adjacent gallery forest (both cerrado s.l. habitat) was made with the aim of identifying the anatomical characteristics of ecological value and correlating them with the environmental conditions. The anatomical features that vary, in general, between the two habitats are: growth ring distinctness (well or poorly defined); tyloses and deposits (more abundant in cerrado specimens); gelatinous fibres (more evident in cerrado specimens and in different patterns between habitats); variation in paratracheal and banded parenchyma (more abundant in cerrado); and more cells per parenchyma strand in cerrado. In general, gallery forest specimens have wider vessels, fewer vessels per square millimetre and larger intervessel pits, indicating more efficient water conduction, whereas cerrado s.s. specimens are the opposite, with low vulnerability and mesomorphy indices, demonstrating greater safety under conditions of water stress. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, ••, ••–••.

Perforated ray cells (PRCs) are recorded here for the first time in the roots and branches of Schefflera vinosa, Caryocar brasiliense, Acosmium subelegans, Byrsonima basiloba, B. coccolobifolia, B. verbascifolia and Alibertia concolor which occur in Pratâniaʼs cerrado (SP, Brazil). PRCs are larger than normal ray cells, occurring isolated or in groups of two or more in the same ray, and are present predominantly in the uniseriate portion of multiseriate rays in all species studied. In the roots and branches, the types of perforation plates (PP) of the PRCs are similar to those of the vessel elements (VE) in most species, with the exception of the branches of Schefflera vinosa and the branches and roots of Caryocar brasiliense. The diameter of the PRC plates was greater in the roots than in the branches, but the differences were only statistically significant in Schefflera vinosa, Byrsonima basiloba and B. verbascifolia. In a general way the PRC plates were greater in diameter than the VE plates in both roots and branches of most species.

Young Sessea brasiliensis trees derived from seeds and sprouts after coppicing were analyzed for differences in axial variation of anatomical features. It was hypothesized that 1) quantitative variation in anatomical features in the axial direction would indicate adjustments in water conductivity and mechanical strength along tree height and 2) significant quantitative differences in anatomical features would be observed between trees originating from seed compared to those derived from sprouts after coppicing. Results showed that wood originating from sprouts after coppicing developed differently from wood originating from seeds. Specifically, for seed provenance samples, narrower vessels were observed in the transition zone, whereas for sprouting provenance, narrower vessels were seen in roots and trunk base. Also, when comparing axial variation between seeds and sprouts, vessel diameter was smaller in plants of seed origin in the transition zone, whereas fiber diameter was smaller in trunk top and branch in plants of seed and sprouting provenances, respectively. Higher rays were observed in branch and trunk top when comparing different axial position in both origins. Thus, the first hypothesis is confirmed by significant axial variation in vessels, fibers and rays, and the second hypothesis is confirmed by the significant differences observed between trees of seed and sprout origins. Key words: Cestrum toledoi, ecological wood anatomy, hydraulic conductivity, peroba-d'água, tropical woods. ResumoAnalisamos diferenças anatômicas da madeira no sentido axial em árvores jovens de Sessea brasiliensis provenientes de sementes e de brotação após corte raso. Hipotetizamos que 1) a variação anatômica quantitativa na direção axial indicaria ajustes na condutividade hidraúlica e resistência mecânica ao longo da altura da árvore e 2) há diferenças anatômicas significativas entre as árvores provenientes de sementes, quando comparadas àquelas provenientes de brotação após corte raso. Vasos mais estreitos ocorreram na zona de transição nas amostras provenientes de sementes, e nas raízes e base do tronco nas provenientes de brotação; comparando as duas origens, vasos mais estreitos ocorreram na zona de transição das plantas originadas por sementes. Fibras com menores diâmetros ocorreram no topo do tronco e ramo nas amostras provenientes de sementes e rebrota, respectivamente. Raios mais altos ocorreram no topo do tronco e ramo. Os resultados confirmaram nossas hipóteses, com variação axial em vasos, fibras e raios e diferenças anatômicas entre as plantas originadas por sementes e rebrota. Palavras-chave: Cestrum toledoi, anatomia ecológica da madeira, condutividade hidráulica, peroba-d'água, madeiras tropicais.