Plant Archives Vol. 20 Supplement 1, 2020 pp. 2309-2319 e-ISSN:2581-6063 (online), ISSN:0972-5210 MORPHOLOGY AND PHYTOGEOGRAPHY OF GLUTA (L.) DING HOU- A REVIEW *Namitha L.H. and Suhara Beevy S. Department of Botany, University of Kerala, Kariyavattom, Thiruvananthapuram-695581 (Kerala), India. Abstract This review encompasses a detailed analysis of the morphology and phytogeography of the different species of the genus Gluta. The genus is widely distributed around Southeast Asian region especially outside the eastern regions of the Indian peninsula and it has a sparse distribution with one species each from the Madagascar, South India and Papua New Guinea respectively. The species’ under this genus show distinct morphologic and genetic variation, which is evident in their morphologic characters. The genus includes about 35 species of which the morphology of 27 species are documented and tabulated here. Introduction Inflorescence is a panicle in all species and can be axillary The plants in the genus Gluta (L.) Ding Hou belongs or terminal. Flowers are bisexual, pedicellate, articulate to the family Anacardiaceae and are commonly known or non-articulate and corolla show imbricate and/or as ‘Rengas’ (Stadelman, 1966). The name Gluta comes contorted, rarely valvate aestivation. Petals (4) 5 (8) are from the Latin word ‘gluten’ or ‘glutus’, which is an white often creamish white or red at base or changing to allusion to the petals being glued to the stipe-formed torus pink, can be caducous and if persistent they are enlarged (Craig J., 1849). ‘Rengas’ is a name derived by the in fruits. Sepals are circumscissile, tubular and toothed. indigenous people in Southeast Asia where the plants Stamens ranging from a minimum of 4 to a maximum or flourish. It consists of four genera viz., Gluta, approximately 100 sometimes inserted on conical torus, Melanochyla, Melanorrhoea, Semecarpus and filaments may be glabrous or pubescent, anthers Swintonia, all belonging to the same family. Injured bark dorsifixed. Gynoecium is monocarpellary, sessile or of these plants secretes a toxic resinous sap that blackens supported by gynophore atop the torus, obovoid, ellipsoid when exposed to air and turns into a resin that causes or subglobose, glabrous or pubescent, pseudonumerous, allergic dermatitis. (Lachapelle, 2014). In spite of which style filiform, lateral or sublateral, stigma punctiform, ovule they are widely exploited for its hard, durable crimson shows basal placentation. Fruit is a monolocular drupe heartwood. Reduction of many species in the genus glabrous to wrinkled, stalked or sessile, globose to Melanorrhea to Gluta has resulted in the 35 species reniform. Some species have wind dispersal adaptation distributed mainly in the Myanmar-Malaysia region and due to the presence of persistent, accrescent, winged- one species each identified from Madagascar, South India like petals. Fruit coat can be brown to purplish red to and New Guinea (Hou, 1978). For this review the authors black. Seed cotyledons sometimes incompletely fused, have selected the accepted species in the genus Gluta embryo straight and sometimes slightly curved. (Kubitzki, described in the Plant List. They are mainly trees and 2010). rarely of shrubby nature. The trunk shows a gradient of Many species now classified in the genus Gluta, was greyish to reddish brown colour. Leaves are evergreen placed under Melanorrhea by earlier taxonomists. They or deciduous, arranged spirally, sometimes aggregated were initially separated based on number of stamens into pseudo whorls and are alternate, simple, entire, (Wilkinson, 1983). The genus Gluta was established by petiolate, rarely subsessile or sessile, mostly coriaceous. Linnaeus (1771) for G. renghas from Java with 5 stamens *Author for correspondence : E-mail: [email protected] and the genus Melanorrhoea by Wallich (1829) for M. 2310 Namitha L.H. and Suhara Beevy S. usitata from Burma with 20-30 stamens. Gluta has a parts of the world, which shows that vast updation is gamosepalous calyx, 5 petals, 5 stamens and a stipitate needed in this genus to fill up the gaps in the information ovary (cf. Linnaeus and de Villers, 1789). database of the genus. Most Gluta species are not included in the CITES The morphological and phytogeographic data was appendices and are in the Least Concern category in the obtained from extensive literature survey (Tagane et al., IUCN Red List, therefore exploited for its deep red 2019, Quattrocchi, 2016, Chayamarit, 2010, Kochummen, heartwood with darker streaks. With an exception of G. 1997, Kochummen, 1996, Soepadmo and Wong, 1995, papuana from New Guinea in Vulnerable category and Adema et al., 1994, Yoshimoto, 1989, Wilkinson, 1983, G. travancorica from South India in the Near Threatened Halim et al., 1980, Hou, 1978, Smythies, 1965, Tardieu, category (IUCN ver. 2.3, 1994). Heartwood is highly 1962, Pierre, 1898, Kirtikar and Basu, 1918). Data was durable and the colour darken on exposure to sun and also collected from online databases like JSTOR herbaria, wind. Sapwood is a light pinkish-brown to almost white TROPICOS (Missouri Botanical Garden), GBIF (Global and causes severe irritation in some individuals. Due to Biodiversity Information Facility) and Flora Malesiana. the striped pattern in the hardwood they are called by the Morphological and phytogeographical data of 27 trade name Tiger Rengas (Wood-Database). The potential species of the genus are tabulated in table 1. of the trees saw wood waste as a source of natural dye A comprehensive description and characteristics of in the shades of brown with color fastness and long shelf the 27 species studied from literature review are as given life was found in a study on the species G. aptera (Ahmad below. W.W. et al., 2011). Like most trees in family Anacardiaceae, Gluta species also contain dermatitis 1. Gluta aptera (King) Ding Hou: (Syn: causing compounds like pentadecyl (C-15) and Melanorrhoea aptera King) Distributed in Borneo, heptadecyl catechol (C-17) urushiols (Kubitzki, 2010). Malaysia and Sumatra. The tree grows upto 40 m high and has a girth of 60 cm. Have a smooth brown bark, The compound isolated from different species of Gluta leaves are coriaceous, obovate to obovate-oblong or viz., thitsiol from G. usitata, moreacol from G. laccifera elliptic. Petals are white, then changing to red from base (Ward, 2008) and renghol from G. renghas (Lin, 1960, upwards, aestivation is imbricate, oblancolate, puberulous cf. Backer, 1941). outside, sparsely hairy and slightly papillose near the base Speciation is one of the most fascinating phenomena inside, sometimes glabrescent. Stamens (100), 8-11mm, in life forms which is a result of geographic as well as panicles grow upto 3.2 cm long, pubescent especially reproductive isolation. This interspecific variability is when young, glabrescent, sometimes glabrous. Ovary actually vital for the survivability of organisms and it has broadly ellipsoid, obovoid or obliquely subglobose and greatly helped them to adapt in various challenging glabrous. (Smythies, 1965). Fruit is a subglobose to climatic conditions. The genus Gluta is observed to be globose brown coloured drupe (Adema et al., 1994). Plant showing remarkable variation in morphology based on its is poisonous, used for criminal poisoning, cause allergies, current geographic location. Since the genus is mostly chemical irritation of skin, sap can cause dermatitis. A confined to dense virgin forest ranges and due to lack of resinous exudate from the wood can cause severe skin sufficient data a review has not been done till date. But irritation. Smoke of the burning wood can cause severe considering the importance of the genus and its economic irritation of the eyes. The resin obtained from the plant is value, especially timber and resin, a detailed record is to a source of long lasting black ink (Flora Malesiana). The be maintained for future utilization and conservation wood is highly resistant to termite attack and is used for studies. making fine furniture, turnery and cabinet work (Martin, Variability which is as a result of genetic and 1984). environmental or geographic factors and the combination 2. Gluta beccarii (Engl.) Ding Hou: (Syn: of both has enhanced the adaptability of the genus to Melanorrhoea beccarii King) Distributed in the fresh survive in variable habitats ranging from terrestrial to water peat swamps of Borneo and Peninsular Malaysia. coastal and swampy areas. Characters like vivipary which The tree grows upto 33 m tall and a girth of 72 cm. The is a prominent adaptation of plants, to circumvent the trunk has a reddish grey to brownish smooth finish bark. marshy and highly saline environmental conditions in some Leaves are coriaceous, obovate or elliptic, glabrous, Gluta species clearly substantiates their high survivability sometimes puberulous beneath, especially on the midrib and establishment (Jose, 2013), (Kessler, 1996). The and nerves. Petals are white, changing to dark pink, compiled morphological data is as a result of extensive contorted and narrowly elliptic, puberulous outside, field surveys conducted by research groups in different glabrous inside. Stamens (70), 5-10mm long. Inflorescence Morphology and Phytogeography of Gluta (L.) Ding Hou-A Review 2311 Table 1: List of Gluta species studied. S. Habitat Distribution Flower Sepal Stamen Fruit Cotyledon No. Plant & & height color (no. (Drupe) elevation of tree of petals) 1. G.aptera Low land, peat Borneo, White-red Calyptriform 100 Globose Free swamp, lower