Wood anatomy of tribe Detarieae and comparison with tribe Caesalpinieae ( Leguminosae , Caesalpinioideae ) in Venezuela

We studied the wood anatomy of 29 species belonging to 10 genera of the tribe Detarieae, subfamily Caesalpinioideae and compare them with tribe Caesalpinieae. Detarieae is the largest of four tribes of Caesalpinioideae, with 84 genera, only eleven occur in Venezuela with species of timber importance. The specimens were collected in Venezuela and include wood samples from the collection of the Laboratorio de Anatomía de Maderas de la Facultad de Ciencias Forestales y Ambientales de la Universidad de Los Andes, Venezuela, and of the Forest Products Laboratory of the USDA Forest Service in Madison, Wisconsin, USA. The terminology and methodology used followed the iAWA List of Microscopic Features for Hardwood identification of the iAWA Committee, 1989. Measurements from each specimen were averaged (vessel diameters, vessel element lengths, intervessels pit size, fibre lengths and ray height). The species of Detarieae can be separated using a combination of diagnostic features. Wood characters that provide the most important diagnosis and may be used in systematics of Detarieae include: intercellular axial canals, rays heterocellular, rays exclusively or predominantly uniseriate, prismatic crystals common in ray cells, irregular storied structure and fibre wall thickness. For comparative anatomy between Detarieae and Caesalpinieae: intercellular axial canals, heterocellular rays, rays exclusively or predominantly uniseriate, prismatic crystals common in ray cells (in Detarieae) and regular storied structure, fibres septate, fibre wall thick or very thick, rays homocellular, multiseriate rays and silica bodies (in Caesalpinieae). Axial parenchyma is typically a good diagnostic feature for Leguminosae, but not for Detarieae and Caesalpinieae comparisons. Rev. Biol. Trop. 57 (1-2): 303-319. Epub 2009 June 30.

Some genera of the tribe Detarieae yield commercial timbers, particularly Copaifera, Eperua, Hymenaea, and Peltogyne, this last is known as "Purpleheart" high-quality wood that is widely appreciated for its unusual color and resistance to insects (JUNAC 1981, INIA 1996, Barneby et al. 1998, Aristeguieta 2003).Others genera such as Brownea and Dicymbe are important ornamental trees, in gardens, city avenues and parks (Barneby et al. 1998, Aristeguieta 2003).Medicinal plants such as Copaifera are of high industrial value for their gum or balsam of Copaiba for medical treatments, manufacturing of varnishes and shellacs, and as a fixative of fragrances in soaps and perfumes.The Elizabetha genus yields a hallucinogenic drug, while Hymenaea genus is used for food and forage, medical treatments, canoe building and manufacturing of varnishes (Mabberley 1997, Barneby et al. 1998, Aristeguieta 2003).Some Dicymbe, Eperua, Heterostemom and Macrolobium species are endemic to the Venezuelan Guayana (Barneby et al. 1998).
This paper provides information about wood anatomy of native genera of the tribe Detarieae, that has not been adequately studied, and to compare them with the tribe Caesalpinieae (Espinoza de Pernía and Melandri 2006b).The microscopic wood anatomy of both tribes was studied because of its great importance in the timber industry and the complexity of its anatomy.The anatomical descriptions provide tools for the identification of the genera and groups within the tribe.

MATERIALS AND METHODS
Microscope slides from 70 wood samples representing 28 species from 10 genera the tribe Detarieae were examined (only 11 genera of the tribe are distributed in Venezuela: Brownea, Copaifera, Crudia, Cynometra, Dicymbe, Elizabetha, Eperua, Heterostemon, Hymenaea, Macrolobium, Peltogyne).The majority of the specimens were collected in Venezuela and includes specimens from the wood collection at the Laboratorio de Anatomía de Maderas de la Facultad de Ciencias Forestales y Ambientales de la Universidad de Los Andes, Mérida, Venezuela (MERw) and at the USDA Forest Service, Forest Products Laboratory, Madison, Wisconsin, USA (MADw and SJRw).
We followed the List of Microscopic Features for Hardwood Identification (IAWA Committee 1989) for terminology and methodology.The following characters were recorded for each specimen studied: presence/absence of growth rings, porosity, vessels distribution, intervessels pit size, vestured pits, fibre wall thickness, septate fibres, axial parenchyma patterns, number of the cells per axial parenchyma strand, ray size in height and width in cells, composition ray cell, storeyed structure, prismatic crystals, silica bodies, and axial canal, among others characters.Generic descriptions follow in alphabetical order and features not listed in the generic descriptions are either absent or do not apply.For vessel diameters, vessel element lengths, fibre lengths and ray height 25 measurements were taken from each specimen and averaged.The measurements are accurate only to the 10 um level, and are reported accordingly.The values reported [e.g. 30 (50-110) 150 μm], are minimum value, range of averages, and maximum value.For other quantitative values the most frequent range is reported.Photomicrographs were taken using a film camera with a light microscope.

DISCUSSION
All wood characters have been recorded, but only the most systematically and diagnostically important ones are displays in Table 1 and the following discussion.These characters emphasized the anatomical information to help in the identification of the species and genera of the Venezuelan Detarieae.Diagnostic features for reliable identification and potentially phylogenetically valuable information within the tribe Detarieae include: fibre wall thickness, ray composition, ray width, intercellular axial canals and storied structure, parenchyma type and prismatic crystals in ray cells.Quantitative features also vary (see Table 1), but most vary too much to be useful in identifications or comparisons.The exceptions are vessels per mm 2 (e.g.species of Peltogyne) ray width (e.g.species of Hymenaea) and intervessel pit size.Vessels per mm 2 and ray width are a good diagnostic quantitative character in these groups.

Comparison of Detarieae with Caesalpinieae
All legume woods have simple perforation plates, alternate intervessel pitting, vessel-ray pits similar to intervessel pits in size and shape, fibres with simple pits, vestured pits (with some exceptions) and in general axial parenchyma with mostly 2-4 cells per strand.In general, the species of the subfamily Caesalpinioideae have medium to thick fibre walls, aliform, confluent and marginal parenchyma, homocellular rays or with a row of square or upright marginals cells, biseriate rays non-storeyed and prismatic crystals in chambered axial parenchyma cells (Baretta-Kuipers 1981, Höhn 1999, Herendeen 2000, Gasson et al. 2003, Espinoza de Pernía and Melandri 2006a,b).While, the following wood characters provide the most systematically important characters between Detarieae and Caesalpinieae: Fibres: septate only in Schizolobium (Caesalpinieae) and are absent in Detarieae genera.Usually thin to thick walled in Detarieae and thick and very thick in the most of Caesalpinieae.
Intercellular axial canals: the presence and distribution of axial canals is a good diagnostic and systematic character in Detarieae.They are found in long tangential lines and immersed in bands of marginal parenchyma in Copaifera and Eperua (Detarieae tribe), also reported and discussed by Barettta-Kuipers (1981), Détienne et al. (1982), Détienne and Welle (1989), Miller and Détienne (2001) and Gasson et al. (2003)    Prismatic crystals are common in subfamily Caesalpinioideae, particularly frequent in axial parenchyma cells, however a of number important genera of the Detarieae tribe also have prismatic crystals common in ray cells, usually one crystal per cell or chamber: Brownea, Cynometra, Dicymbe, Elizabetha, Heterostemon and Macrolobium (except M. rubrum).This observation coincides with recorded by Détienne et al. (1982), Détienne and Welle (1989), Miller and Détienne (2001).Silica bodies only present in the tribe Caesalpinieae (Tachigali and Sclerolobium species), absent in all Detarieae studied, also discussed by Koeppen (1980), Barettta-Kuipers (1981) and Gasson et al. (2003).
Vessels per mm 2 of 2 to 10 in most species of Caesalpinieae and Detarieae tribes, however Peltogyne is very different, presents from 20 to 46 per mm 2 .Intervessel pit size in most Caesalpinieae and Detarieae is commonly medium to large, while in Brownea, Cynometra, Dimorphandra, Heterostemon and Mora, there is a tendency towards minute to small.Finally, in summary the diagnostic features important for identification of the tribe Detarieae and for comparison with Caesalpinieae are: intercellular axial canals, rays heterocellular, rays exclusively or predominantly uniseriate, prismatic crystals common in ray cells, storied structure, fibre wall thickness and absent of silica bodies.The interpretation of homocellular versus heterocellular rays in Copaifera, Cynometra and Dicymbe is not consistent in the literature with similar inconsistencies for the tribe Caesalpinieae (Espinoza de Pernía and Melandri 2006b).Therefore, this character may need to be re-examined in the wood of other legumes and possibly re-defined for use in keys and descriptions.In addition, the distribution of these diagnostic features in particular groups, often in agreement with phylogenies and also certain characters may have some relationship to ecological conditions (e.g.vessels per mm 2 , intervessel pit size, axial parenchyma abundance and fibre wall thickness).
650 m in height.Storied structure not observed, only rays irregularly storied (rays in echelon) in M. molle.

TABLE 1
Synoptic table of anatomical features

TABLE 1
Synoptic table of anatomical features