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Comparative anatomy of Sirhookera (Orchidaceae) growing in Western Ghats of Southern India

Citation

Ravichandran, Koshila Ravi; Mayakrishnan, Balachandar; Kanithottathil, Jinsha; Thangavelu, Muthukumar (2020), Comparative anatomy of Sirhookera (Orchidaceae) growing in Western Ghats of Southern India, Dryad, Dataset, https://doi.org/10.5061/dryad.sf7m0cg2x

Abstract

We compared the anatomical characteristics of vegetative organs, peduncle and mycorrhizal morphology of Sirhookera belonging to the subfamily Epidendroideae (Orchidaceae) to identify the anatomical markers for identification of Sirhookera species as well as to their ecological adaptations. The leaves are hypostomatic bearing tetracytic stomata and the walls of subsidiary cells are smooth in Sirhookera lanceolata and undulate in Sirhookera latifolia. The leaves on the adaxial and abaxial surfaces are covered by thick cuticle. The hypodermis is dimorphic and present on both sides of the leaf; chlorenchyma is homogenous and the vascular bundles are collateral. The rhizome of Sirhookera possesses a single-layered epidermis, thick cuticle, thin-walled parenchymatous ground tissue containing starch grains and scattered collateral vascular bundles. A thick-walled sclerenchymatous band separates the cortex from the parenchymatous ground tissue comprising of banded cells in the peduncle. Starch grains are present in ground tissue of S. latifolia peduncle. The roots consist of the velamen, ∩-thickened exodermis, thin-walled cortex consisting of water storage cells, O-thickened endodermis and vascular cylinder with parenchymatous pith. Starch grains are present in the root cortical cells of S. lanceolata but absent in S. latifolia. The fungal pelotons that aids in nutrition acquisition is evident in the root cortical region in both species. The study revealed significant variations in the anatomical characteristics in both species and most of the anatomical features of Sirhookera relate to their ecological adaptations.