Vegetos
(An International Journal of Plant Research & Biotechnology)
(eISSN: 2229-4473)
Comparative anatomy and taxonomic insights of the endemic Indian genus Haplanthodes (Acanthaceae)
*Article not assigned to an issue yet
Research Articles | Published: 06 May, 2026
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Keywords: Andrographideae, Spiny bottlebrush, Endemic, Morpho-anatomy, Taxonomic delimitations
Abstract
The genus Haplanthodes (family: Acanthaceae) is endemic to India and comprises five taxa. Due to their morphological similarities, they are often difficult to distinguish from one another. To clarify interspecific relationships and identify key diagnostic characteristics, a comparative study was conducted examining the organoleptic, macroscopic, and anatomical features of the stems, roots, cladodes, and leaves of all five taxa. The findings suggest that both external and internal morphological features provide valuable insights into the macro and microstructural classification of Haplanthodes. The genus has a unique morphological feature that sets it apart from other genera in the Acanthaceae family, such as Andrographis and Haplanthus. At the species level, H. verticillata, cladodes are stiff, spinose, and verticillate; whereas in H. tentaculata, they are of similar size but smooth and non-spinose; in H. plumosa, the lower half of the cladodes are densely hairy, giving a plume-like appearance; and in H. neilgherryensis and H. neilgherryensis var. toranganensis, they are thin, soft, and filiform. These features are particularly useful for species identification in the absence of reproductive structures. Anatomical differences in the leaf midrib also support species-level distinctions: H. verticillata exhibits a plano-convex, squarish outline with conjoint, closed, collateral vascular bundles; H. plumosa, H. neilgherryensis, H. tentaculata, and H. neilgherryensis var. toranganensis show a convex, triangular to wavy-squarish outline with similar vascular bundle configurations. These foundational anatomical and morphological data contribute to a more robust framework for species delimitation within the genus and provide a basis for future studies within the tribe Acantheae and the broader Acanthaceae family.
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Author Information
Biodiversity & Palaeobiology (Plants & Diatoms) Group, Agharkar Research Institute, Pune, India