Wood anatomy of the Palaeotropical Melastomataceae

The wood anatomy of the palaeotropical Melastomataceae is described in detail on the basis of 134 samples of 107 species from 36 genera. On the wood anatomy, three subfamilies are recognized, Memecyloideae, Melastomatoideae, and Crypteronioideae. The Memecyloideae stand out through their fibre-tracheids, the deviating fibre length/vessel member length ratio, and the scanty paratracheal to aliform parenchyma. The Melastomatoideae are characterised by libriform fibres showing fibre dimorphism and rays composed of erect, square, and weakly procumbent cells (also in Memecyloideae p.p.). The subfamily Astronioideae is abolished; Pternandra is transferred to Memecyloideae, the Astronieae fit perfectly in the Melastomatoideae. Within Melastomatoideae the tribes are not easy to separate. The subtribe Dissochaetineae (all climbers) of the Dissochaeteae stands out because of its multiseriate rays, subtribe Medinillineae has scalariform inter-vessel pits; Astronieae have longest vessel members of the palaeotropical Melastomataceae, uniseriate rays, and bands of deviating fibres in which axial parenchyma is scarcely present: in the Osbeckieae apotracheal parenchyma bands (probably originated through fibre dimorphism) characterise the wood of Dichaetanthera; it is proposed to combine Oxysporeae and Sonerileae to one tribe Sonerileae; on the basis of the inter-vessel pitting two subtribes are recognized, different in delimitation from the two original tribes. The family Crypteroniaceae s.s. (Axinandra, Crypteronia and Dactylocladus) is incorporated in Melastomataceae as a separate subfamily. The scalariform inter-vessel pits, present in palaeotropical Melastomataceae only, must be interpreted as a specialization from the alternate pattern. Raphides are present in one species of Bredia, B. tuberculata. Clustered crystals are observed in the axial parenchyma and rays of Dichaetanthera. Large elongate crystals are present in the parenchyma of the strands of axially included phloem of the Memecyloideae. Variation in quantitative characters (vessel member length, vessel diameter and frequency) can partly be explained from the ecological preference of the species concerned. Wood anatomical differences between lianas and erect relatives are discussed.