Peter Gasson

A method for measuring cell diameter and area in transverse seetions of wood with an automatie image analyser is described. The parameters measured were vessel lumen area, vcssel lumen diameter and percentage conductive area (PCA). The automatie image analyser was used to measure these parameters in root, trunk and branch wood of pedunculate oak (Quercus robur L.) and European beech (Fagus sylvatica L.). The measurements were compared with those obtained with a digitiser from sampies of holm oak (Quercus ilex L.) and Turner's oak (Quercus × turneri Willd. = Quercus ilex × Q. rabur). Both techniques permit the rapid examination of transverse seetions of wood and the accumulation of a large data base. The automatie method is more rapid than the semi-automatic one using a digitiser, the measurements are more accurate and the method is less labour intensive. The data obtained permit the interpretation of variation in vessel size and distribution throughout the tree and relate this to the water carrying capacity .of the xylem. In Quercus robur, PCA and vessel diameter tend to increase [rom immature aerial, to mature aerial, to root xylem, whereas in Fagus sylvatica although vessel diameter tends to show the same trend, PCA does not. The conclusions reached for Quercus ilex and Q. × turneri were less definite.

Peter Gasson

Traditional wood identification techniques using light microscopy are usually sufficient to identify a wood sample to the genus level. In some cases CITES legislation requires identification to species level, which is difficult or impossible using traditional light microscopy. This paper concentrates mainly on the identification challenges posed by CITES, particularly with ramin (Gonystylus spp.), Brazilian Rosewood (Dalbergia nigra) and Agarwood (Aquilaria and Gyrinops species). All the other CITES listed timbers and some other taxa that are traded or confused with protected species and might in the future be protected by legislation are also discussed. There are several new non-anatomical techniques being tried to make more accurate identifications and these are mentioned where appropriate.

There is a mismatch between legislation and the natural world, and the limitations of the identification process need to be better appreciated by enquirers, especially in relation to CITES enquiries, since species and genus concepts vary among biologists, and can be ambiguous.

Peter Gasson

Peter Gasson

The tribe Swartzieae, like the Sophoreae is a basal member of the Papilionoid legumes, lying at the boundary between this subfamily and the Caesalpinioideae (Polhill ' Raven 1981). Recent surveys have investigated the wood anatomy of 42 out of the 48 genera in the Sophoreae (Fujii ' Baas 1992; Fujii et al. 1994; Gasson 1994; Den Outer ' Van Veenendaal 1992). Similar work is needed on the Swartzieae ( II genera), and in the Caesalpinioideae on Caesalpinieae (47 genera) , Amherstieae (25 genera) and Detarieae (55 genera). The wood anatomy of Swartzieae is described here, the genus Baphiopsis apparently for the first time, and comparison is made especially with Sophoreae . There is no clear delim itation between the two tribes, which is confirmed by cladistic analysis on 12 wood characters of Swartz ieae alone, then combined Swartzieae and Sophoreae. Baphiopsis (Swartzieae) and Baphia (Sophoreae) are so similar anatomically that they should perhaps be in the same tribe, and Bocoa is not uniform anatomically, and may not be a coherent genus. The data presented here will assist in reaching conclusions on the correct delimitation of some genera and tribes in the Papilionoid legumes.

Peter Gasson

The wood anatomy of all three genera in the tribe Dipterygeae, Dipteryx, Pterodon and Taralea is described here in a systematic context. Dipteryx and Pterodon have short, narrow, storied rays and fine intervessel pitting, whereas Taralea has narrow non-storied rays and much finer intervessel pitting. The wood of T. casiquiarensis is much more similar to that of Dipteryx and Pterodon than to its congeners, and a new combination based on both wood and morphological features is being published in Kew Bulletin (Lewis ' Gasson, in press). The Dipterygeae may form an outlying group to the Dalbergieae, although its nearest affinity has been thought to be with Monopteryx (Sophoreae). Here, the wood anatomy of the three genera is compared with that of Sophoreae, Swartzieae and Dalbergieae.

Peter Gasson

Several aspects of the secondary xylem anatomy of oak (Quercus robur L.) branches, trunks and roots are investigated. These are. growth ring width and definition, vessel size (diameter), shape (eccentricity) and distribution, fihre type (ge1atinous or normal), and fibre, axial parenchyma and ray distribution. These observations are put in perspective by comparison with beech (Fagus sylvatica L.), and discussed in relation to their implications in wood identification, archaeology, dendrochronology and water relations of the tree.

Peter Gasson

While using the IAWA standard list of characters to describe the anatomy of tropical woods, some characters were found to be open to more than one interpretation. This paper discusses five interrelated vessel characters with reference to observations on 126 woods of Rutaceae. The reasons for am biguity in certain characters are given, and recommendation for more rigorous interpretation are made.

Pat Denne and Peter Gasson

Differences in ray structure between root- and stem-wood of softwoods can cause confusion in identifying roots using keys based on stem-wood anatomy. Comparison of root- and stem-wood rays of Larix decidua showed root-wood had fewer ray tracheids, taller, wider but shorter ray parenchyma cells, and larger cross-field pits than stem-wood. The implications of these differences are considered in relation to the identification and function of roots.

Peter Gasson and Pieter Baas

Peter Gasson and Polly Webley

The genus Exostyles consists of two to three species from Brazil. This paper describes the wood of E. venusta Schott, completing generic coverage of the wood anatomy of the tribe Swartzieae as defined by Cowan (1981). Small twigs from herbarium sheets of E. glabra and E. amazonica (labelled E. venusta) were also examined. Exostyles wood anatomy is compared with that of the other genera in the tribes Swartzieae (Gasson 1996) and Sophoreae (Gasson 1994; Fujii et al. 1994), and is very similar to three closely related genera of Swartzieae, Zollernia, Harleyodendron and Lecointea.