Micromorphology and distribution of Trichomes in the family Fabaceae Lindl.
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Date
2019-08
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Fabaceae, also called Leguminosae or pea family, is the third largest Angiosperm family with about 741 genera and 20200 species on Earth. Large number of Fabaceae members exist in Pantnagar area and a study of trichomes of 26 species was conducted during 2018-19 to understand diversity in structure of trichomes and distribution of trichomes on different surfaces. Different surfaces of plant parts- stem, petiole, rachis, both surfaces and margins of leaf or leaflets, stipule, bract, sepal, petal, androecium, gynoecium, pod, were examined under light microscope for the presence, distribution and structural diversity of trichomes. Studied species belongs to 4 subfamilies of Fabaceae following recent and highly phylogenetic system of legumes by Legume Phylogeny Working group. All 26 species bear trichomes on any one or more surfaces examined. Gynoecium bear trichomes in maximum (20) species, followed by sepal and leaf axes (19 spp.), and stem and leaves (17 spp.). Stamens bear trichomes in minimum number (5) of species. 32 structural types of trichomes were recorded of which 7 were glandular and 25 were non-glandular types. In 15 species trichomes are only non-glandular types whereas, 11 species bear both glandular as well as non-glandular trichomes. Non-glandular, unicellular, subulate (NU-subulate) trichomes are most common in Fabaceae and recorded in 16 species while among the glandular trichomes, glandular, multicellular, uniseriate, clavate (GMU-clavate) trichomes are more common and recorded in 7 taxa. Maximum seven types of trichomes were recorded in Bauhinia tomentosa. In Caesalpinia pulcherrima trichomes are present only at the base of filaments. In family Fabaceae trichome structure and distribution were found useful for differentiating species within genera thus proves their systematic utility. The study concludes that wide variety of trichomes exists in Fabaceae, though the exact role of trichomes is yet to be ascertained. Presence of trichomes on gynoecium in more than two-third species suggests their role in protection of developing pods and seeds by warding off creeping insect pests.
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