Indian J. Genet., 80(1) 77-83 (2020) DOI: 10.31742/IJGPB.80.1.10 *Corresponding author’s e-mail: pravin.patil99@gmail.com 1 Present address: Shankarlal Agrawal Science College, Salekasa, Gondia 441 916 Published by the Indian Society of Genetics & Plant Breeding, A-Block, F2, First Floor, NASC Complex, IARI P.O., Pusa Campus, New Delhi 110 012; Online management by www.isgpb.org; indianjournals.com Significance of seed trichome micro-morphology in systematic treatment of Abelmoschus-Hibiscus complex Pravin Patil 1 , S. K. Malik and K. V. Bhat National Bureau of Plant Genetic Resources, Pusa Campus, New Delhi 110 012 (Received: March 2019; Revised: January 2020; Accepted: January 2020) stable and seem to reflect genetic-phylogenetic differences in the plants concerned. The significance of SEM study lies in the fact that plant epidermis is thick and most stable (least affected by environment), covers almost all the plant parts. Therefore, during last few decades features of seed micro-morphology have been studied and reported to be useful to resolve taxonomic problems in various critical and overlapping taxonomic groups (Shavvon et al. 2012; Bona 2013; Azevedo et al. 2019; Tavakkoli and Assadi 2019; Kaya et al. 2019). The singular or multicellular epidermal hairs, known as trichomes have several functions in plants which include defense against insects, production of chemicals which deter insect and herbivores from feeding. Trichomes have a role in secretion of nectar, resins, mucilage, terpens etc in several of the plant species. Several type of trichomes have been reported and their variations studied and their utility in relation to plant taxonomy have been well demonstrated (Sudhakaran and Ganapathi 1993). Family Malvaceae, commonly known as ‘mallow family’ comprises various economically important genera such as Gossypium (Cotton), Corchorus (Jute), Hibiscus (Kenaf) and Alcea, Malva (ornamentals importance) in tropical and subtropical regions (Sivarajan and Pradeep 1996) and therefore, has attracted great interest of plant systematists. Apart from these, genus Abelmoschus (Malvaceae) is very important due to its tasty, mucillagenous, nutritionally valuable, immature fruits bearing species A. esculentus (L.) Moench. Species of Abelmoschus exist in wild, semi-wild and cultivated forms, reflecting the vast ecological adaptation of the genus to different eco- Abstract Indian sub-continent is rich in genetic diversity of various species of genus Abelmoschus and Hibiscus. Several of these species exist in wild, semi-wild and cultivated forms due to favorable eco-geographical conditions. Seed morphology (especially trichome structure) of Malvaceae members is known to be diverse, but variation patterns have never been critically studied in these complex genera. In the present paper usefulness of this important character for the generic differentiation between Abelmoschus (13 species) and Hibiscus (10 species) using scanning electron microscopy of seed has been described. Primary generic differentiation has been derived using basic seed trichome morphology i.e. unicellular (un-fused) and multi-cellular (fused) which was spiral or non–spiral, spread evenly or localized in all the studied taxa. The presence of unicellular and un-fused trichomes on seed coat surface in the Abelmoschus species provides an additional and significant micro-morphological differentiation to delineate the boundaries between genus Abelmoschus and Hibiscus. Key words: Abelmoschus , generic differentiation, Hibiscus , micro-morphology, seed trichome, SEM, Abelmoschus-Hibiscus complex Introduction Heywood (1971) and Cole and Behnke (1975) drew attention to the importance and impact of scanning electron microscopy (SEM) in solving systematic problems in various critical species and genera of angiosperms. SEM studies have been made primarily on seeds, trichomes and pollen ornamentation with respect to study the species or sub-species delimitation and differentiation. According to Barthlott (1981) epidermal and seed surface features are more