WOOD ANATOMY OF THE HIPPOCRATEOIDEAE (CELASTRACEAE)

In this paper the wood anatomy of the subfamily Hippocrateoideae of th e Celastraceae is treated. Halle's division (1986, 1990) of the subfam ily into four tribes, chiefly based on material of tropical Africa: vi z. Salacieae, Campylostemoneae, Helictonemeae and Hippocrateae is foll owed. In a recent issue of the Flora of the Guianas the Hippocrateacea e - there treated as a separate family - were divided into Hippocrateo ideae and Salacioideae. This bipartition was reflected in the wood str ucture of the genera studied (Mennega 1994). Here the wood structure o f all genera worldwide (24), except the Asian genus Arnicratea, is des cribed. It appeared that again a subdivision into two distinct anatomi cal groups could be made, with the three last tribes mentioned above s howing the same characteristic structure as found before in New World Hippocrateae /Hippocrateoideae. The most important features of this gr oup are the presence of very wide and very high rays, in a number of g enera with unlignified ray cells at the growth ring border, the absenc e of included phloem tissue, and in many species an intruding bark res ulting in an indented wood pattern in stem cross sections or even an i ntricate pattern of deep furrows. The Salacieae/Salacioideae on the ot her hand are characterized by narrow, not exceptionally high rays, abs ence of unlignified ray cells, the occurrence of septate fibres in a p arenchyma-like distribution, and often by the presence of included phl oem tissue, either as isolated strands or more often as conspicuous co ncentric bands, or as irregular bands with radial connections. Feature s present in all genera are: vessels with simple perforation plates, p reponderance of solitary vessels, wide and narrow vessels distributed at random, alternate pitting; fibre-tracheids, and libriform nonseptat e and septate fibres present; axial parenchyma scanty paratracheal or as rare isolated strands; rays heterogeneous, the cell types irregular ly distributed, rhombic crystals numerous, often in characteristic rad ial distribution. Campylostemon, considered in the past by some taxono mists as belonging in Celastraceae or as intermediate between Hippocra teaceae and Celastraceae, closely resembles Hippocrateae in its wood a natomy. And it is especially this group that by its characteristic fea tures - like the wide rays - is more different from Celastraceae in ge neral than Salacieae, which have several features in common with gener a of Celastraceae.