135 PHYTOLOGIA BALCANICA 18 (2): 135 – 140 Sofia, 2012 Taxonomic significance of the epicalix in the genus Hibiscus (Malvaceae) Taiwo A. Ayanbamiji 1 , Oluwatoyin T. Ogundipe 2 & James D. Olowokudejo 2 1 Department of Biological Sciences, Bowen University, Iwo, Nigeria, e-mail: taiwoayanbamiji@yahoo.com (corresponding author) 2 Department of Botany, University of Lagos, Akoka-Yaba, Lagos, Nigeria. Received: April 20, 2012 ▷ Accepted: July 06, 2012 Abstract. The epicalyx may be defined as a whorl of bracts below or beside the calyx, occasionally referred to as an extra calyx. Such structures attract little emphasis in floral morphology because they are absent in many flowering plants. A detailed study of the morphology of epicalyxes in some species of Hibiscus L. was carried out. The number, size, shape, structure and orientation of bracteoles of the epicalyx were found to be useful in the identification of species. On the basis of cohesion and adhesion of the epicalyx to the calyx, the species of Hibiscus can be divided into four major taxonomic groups. The morphological features of the epicalyx are suspected to be phylogenetic and, therefore, are seen as preliminary tools for the review of the sections in this genus. A dichotomous key for identification of the species is prepared, based exclusively on the reported features. The floral formulae are also presented for the first time. Key words: adhesion, bracteoles of epicalyx, cohesion, Hibiscus, taxonomic groups. Introduction The genus Hibiscus L. belongs to the family Malva- ceae. The family comprises 88 genera and 2300 spe- cies distributed across the world (Heywood 1978; Burkill 1997). Members of this family are found in all regions, except in the very cold ones, but are most numerous in the temperate warm and tropical coun- tries. The family has four tribes, Malopeae, Malve- ae, Urenea and Hibisceae (Hutchinson 1967; Willis 1973). The species of Hibiscus are of great economic im- portance as sources of fibres, medicinal products, food, and cosmetics. They are used in the fashion in- dustry and as agriculturally and ecologically benefi- cial plants (Dalziel 1937; Esau 1960; Metcafe & Chalk 1965; Hutchinson 1967; Ugborogho & Shofoyeke 1983; Burkill 1997; Akpan 2000). The Hibiscus species are annual or perennial herbs, shrubs or trees. Leaves are often palmately lobed. Flow- ers showy, commonly solitary with five petals, five se- pals and pedicels usually articulated. Epicalyx and ca- lyx are occasionally persistent, inflated and enlarged in fruit. The ovary has five carpel and 5-capitate stigmas, which are essentially constant (Ghazanfar 1989; Hutch- inson 1967). The epicalix is a ring of modified leaves/ bracts that looks like an extra calyx below or adjacent to the proper calyx, and may resemble a calyx (Olorode 1984; Sharma 2008). The units in a flower are called bracteoles and all bracteoles in a flower make the epica- lyx. According to Fryxell (1997) and Alam & al. (2006), the genus exhibits considerable taxonomic complexity and is so heterogeneous that it is hard to identify any distinguishing features between some species. The pre- sent study is aimed at using the characteristic features of the epicalyx as taxonomic tools in the genus Hibiscus.