ANATOMY AND IDENTIFICATION OF FIVE INDIGENOUS RATTAN SPECIES OF GHANA E. Ebanyenle & A. A. Oteng-Amoako Forestry Research Institute a/Ghana, UST Box 63, Kumasi, Ghana ABSTRACT Stem anatomy of Calamus deeratus, Eremospatha hookeri, Eremospatha macrocarpa, Laccosperma acutijlorum and Laccosperma secundijlorum growing naturally in Ghana were investigated to explore the possibility of using anatomical features to distinguish between them. Although the anatomy of all the stems of the five species investigated exhibited a common monocotyledonous structure, they differed considerably in many of their anatomical features. Anatomical features of taxonomic and diagnostic significance at genus level included: the number of metaxylem vessels and phloem fields in a vascular bundle and type of ground parenchyma. However, the most important anatomical features to distinguish species are the epidermal cell size and shape. A combination of several anatomical features is used to develop a tentative identification key to thefive rattan species occurring naturally in Ghana. Keywords: Ghana, indigenous, rattan, anatomy, identification INTRODUCTION another and sometimes the same name is given to more than one species. In Rattan is a collective term commonly used addition, poor harvesting techniques and for spiny palms belonging to the subfamily over-exploitation from its natural habitat Calamoideae of the family palmae. This without cultivation have led to scarcity of subfamily comprises 13 genera with more economic rattan supply, especially than 600 species (Uhl & Dransfield, Eremospatha spp, the species of highest 1987). Ten genera with their species occur demand in Ghana. Hence, the future of the in the Southeast Asian region and four rattan industry upon which many rural genera of 19 species occur in West and people depend appears to be threatened Central Africa. Of these four genera: (Oteng-Amoako & Obiri-Darko, 2000). Laccosperma, Eremospatha, Oncocalamus are endemic to West and Central Africa Cultivation of rattans remains the best region while Calamus is a native to both option for sustaining the industry. Hence regions (Dransfield, 1981; Sunderland, basic comprehensive research is needed to 1997a). identify taxonomical, ecological, physical and anatomical properties that would help In contrast to the situation in Southeast in conservation of genetic resources and Asia, knowledge of Africa rattans is still lead to efficient utilization of rattans in not sufficiently known in spite of the very Ghana. The primary objective of this study important role they play in the local therefore was to determine anatomical economy of most West and Central properties of five indigenous rattan species African countries. Consequently, the rattan of Ghana to aid in identification of their industry is beset with many problems stems. including misidentification of semi~ processed rattan stems. Once the rattan MATERIALS AND METHODS stems are cut and leaf sheaths removed, identification of the stems become A total of five species, comprising three difficult. Many rattan collectors group genera, viz: Calamus, Eremospatha and stems on the basis of stem diameter Laccosperma were used in this study. irrespective of botanical names. The local Samples were collected from three names often vary from one locality to different forest types of Ghana viz.: Wet Ghana J. Forestry, Vol. II (2) 2003 77 Anatomy and identification of five indigenous rattan species E. Ebanyenle & A. A. Oteng-Amoako Evergreen (WE), Moist Evergreen (ME) Five each of transverse and longitudinal and Moist Semideciduous (MSD) (Table sections of 15-25!lm thickness were then 1). Within a forest type, five matured made for each of the 165-microtomy stems were collected randomly from samples on a sliding microtome. The different growing clumps for each species. sections were first washed in water and Due to difficulty in collection, the entire then stained in 1% safranin in 50% ethanol length of stems could not be obtained. solution for about 10-20 minutes. After Herbarium samples for the taxonomic staining, they were washed in water and identity of the samples were also collected then dehydrated in increasing and kept in the herbarium of Forestry concentration of ethanol: 30, 50, 70, 85, Research Institute of Ghana (FORIG). 90 and 100% before being mounted in Canada Balsam. The sections were kept in For anatomical investigations, a sample of xylene and creosote solution (I :1) and 1em length at mid internode level was then xylene for hardening. All prepared removed from the second basal, middle slides were dried at 60°C overnight. The and top internodes positions from each of prepared slides of various species were the collected stem. It was then subdivided then examined under light microscope into two diameter flanks. One flank was following a prepared checklist of used for microtomy and the other for anatomical features. maceration (Fig. 1). The sample for microtomy was softened by first saturating it with water and later keeping it in a mixture of ethanol and glycerol (1: 1) in labeled containers for an average period of about 20-30 days. 5- ME5MSD-15525,511.928Total1319.718.110.316.0811(mm)Mean9.9(m)Length Mean 55 TABLE 1 Diameter CalamusDranstH.andWend!.NameWend!.H. Wend!.of deeratusSpecies G, Mann and H. WE EremospathaLaccosperma*Laccosperma*EremospathasecundiflorummacrocarpahookeriacutiflorumG, Mann(Becc.)p,G. BeauvMannandJ. *Speciesnot readilyavailable at MSD and ME Species and Samples Used for theNumberStudyof Stems Ghana J Forestry, Vol. 11 (2) 2003 78 Anatomy and identitlcation of five indigenous rattan species E. Ebanyenle & A. A. Oteng-Amoako Anatomy (l cm) Microtomy Q. ~.1;.' M",orotioo C ~' . A B Fig. 1 Schematic diagram of (a) Rattan stem showing three levels: second basal, middle and top internodes (b) Internode showing mid portion (shaded portion) and (c) lem length sample and diameter flanks for microtomy and maceration. From each of the samples for maceration, cells were rinsed with water and mounted two splits of matchstick size were taken temporarily in dilute glycerol for from the core and the periphery portions measurements of cell dimensions. and kept in separate vials containing mixtures of 6% hydrogen peroxide and Measurements were made with an 97% acetic acid. The specimens were then eyepiece scale of 100 divisions after the incubated at 60°C for 3 days to obtain micrometer value has been determined for complete macerations. The macerated all the objective lenses. The radial length Ghana J Forestry, Vol. 11 (2) 2003 79 Anatomy and identification of five indigenous rattan species E. Ebanyenle & A. A. Oteng-Amoako and width of at least 20 epidermal cells RESULTS AND DISCUSSION were measured in each sample. Cortex General Stem Anatomy width was determined from the epidermis to the periphery of the central cylinder The general stem anatomy of the species from 10 radial measurements per sample. investigated is similar to some African Vascular bundle diameter was measured rattan species described by Weiner and along direction of maximum diameter Liese (1992, 1993b, 1994) and Oteng• (Bhat et al., 1993). Number of vascular Amoako & Ebanyenle (2000). All the 5 bundle per square millimeter was species investigated were distinctly made determined by counting the number of up of epidermis, cortex and central vascular bundles within an eyepiece scale cylinder (Figs. 2 to 6). grid of a field area of 1.4963mm2• An average of five counts per section was All species exhibited a single layer converted to correspond to an area of epidermis consisting of unlignified Imm2• Fiber, conducting tissue and parenchyma cells. The epidermis was parenchyma proportions were determined covered with siliceous layer interspersed from each sample using a lOx objective with few stomata cells. The cortex of all lens and lOx eyepiece with a dot grid scale species consisted of fiber bands, of 20 points. The dot grid scale was placed rudimentary vascular bundles embedded in five times progressively from the parenchyma cells of varying shapes and periphery of the central cylinder towards sizes lying ring-like around the central the centre of the central cylinder. At each cylinder (Figs. 2c, 3c, 4c, 5c and 6c). placement, the number of points covering any tissue was counted and expressed as a The central cylinder of all the species was percentage of the total number of points. generally composed of vascular bundles of At least 10 wide metaxylem vessels from varying sizes and structure, embedded in the central one-third of the diameter of ground parenchyma (Figs. 2a, 3a, 4a, 5a transverse section were selected from each and 6a). The vascular bundle consisted of sample to estimate the mean diameter of conducting tissue (xylem and phloem), the widest vessels (Klotz, 1978). The which was surrounded by a fiber sheath diameter of the metaxylem vessel was and parenchyma (Figs. 2b, 3b, 4b, 5b and determined, based on the mean values of 6b). The xylem was either composed of two measurements taken at right angles to one large metaxylem-vessel (Figs. 2b, 5b one another. A minimum of 10 vessel and 6b) or two metaxylem-vessels (Figs. elements was measured from each 3b and 4b) and a cluster of protoxylem• macerated core sample for estimation of vessels (Figs. 2b, 3b, 4b, 5b and 6b). In all its length. Fiber length, width, lumen and species investigated, tylose-like structure double wall thickness were measured on was found in few metaxylem-vessels 50 complete and straight fibers per (Figs. 2b and 3b). The phloem consisted of macerated sample. Terminology for different number of sieve tubes with description followed the recommendations companion cells (Figs. 2b, 3b, 4b, 5b and of IAWA Committee (1989) and Weiner 6b). Raphides were occasionally seen in and Liese (1990). Photomicrographs were the tube-like structure in cross and made using a photomicroscope at Wood longitudinal sections of ground Anatomy Laboratory of FORIG. The parenchyma (Fig. 2d). Liese & Weiner development and printing of the (1989) and Weiner & Liese (1994) also micrographs were however done by reported of the occurrence of raphides in private photo-laboratory in Kumasi.