Abstract
A comparative anatomical study of eight species of Dioscorea L. from Meghalaya, North East India was carried out in order to evaluate the taxonomic significance of anatomical characters to differentiate the species. Characters were coded and analyzed by PCA and cluster analysis. The combination of selected qualitative and quantitative anatomical characters of foliar epidermis, stem and petiole were significant for identification of species. The characters that contributed most to the separation of the species were type of stomata, length of stomata, stomatal index, leaf epidermal hairs, stem epidermal hairs, layer of stem sclerenchyma, number of vascular bundle in outer ring and inner ring of stem, paired or unpaired metaxylem, presence of phloem at both ends or at one end, presence or absence of starch grain in stem, petiole epidermal hair and presence or absence starch grain and crystal in petiole. An indented dichotomous key based on anatomical characters was constructed to distinguish and identify the species.Keywords: Anatomy; Dioscorea; Cluster Analysis; Principal Component Analysis; Systematics.Bangladesh J. Plant Taxon. 24(1): 5363, 2017 (June)
Highlights
Dioscorea L., with about 602 species (Coursey, 1967) in the tropical and subtropical regions, regarded as the core genus of the family Dioscoreaceae is a pivotal taxon in the evolution of Liliopsida and occupies a basal position among all extant monocotyledonous plants (Chase et al, 2006; Dahlgren, 1989)
The use of anatomical characters or traits for taxonomic studies has proved useful for identification of fragmented plant and herbarium specimens (Metcalfe and Chalk, 1957)
Anatomy can provide useful information for establishing interrelations between taxa at the species and supra species levels. Sometimes it can help in individual identifications
Summary
Dioscorea L., with about 602 species (Coursey, 1967) in the tropical and subtropical regions, regarded as the core genus of the family Dioscoreaceae is a pivotal taxon in the evolution of Liliopsida and occupies a basal position among all extant monocotyledonous plants (Chase et al, 2006; Dahlgren, 1989). About 50 species of Dioscorea in India (Anonymous, 1952) and approximately 28 species are distributed in North East India (Sharma and Hore, 1995). One of the eight hot spots of North East India has wide range of distribution of Dioscorea species in wild habitat. A few species of Dioscorea are consumed as food and used as medicines by the indigenous people of this area in spite of its wide range of distribution. Kunth (1924) divided Dioscorea into four subgenera based on seed morphology. Burkill (1960) divided the genus into 23 sections based on seed characters, tuber characters and male inflorescence morphology. Coursey (1967) divided the genus into 70 sections based on underground tuber. Several authors studied the floristics of the genus including Miege (1968), Milne-Redhead (1975), N’Kounkou (1993), Tellez and Schubert (1994), Miege and Sebsebe (1998) and Ding and Gilbert (2000)
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