Abstract
An investigation was carried out to reveal the taxonomic importance of cypselar features of Vernonia anthelmintica Willd. and Vernonia cinerea Less. through morpho-anatomical manifestations in the plesiomorphic tribe Vernonieae of the dicot family Asteraceae. A light microscopic (LM) and Scanning Electron Microscopic (SEM) study unraveled various morphological features of the cypsela. Among them, apical part, wall surface, surface hairs, nature, structure and arrangement of carpopodium, and stylopodium are taxonomically important traits. Furthermore, presence or absence of glands in wall surface, pappus bristles, testal nature, distribution of crystal and in pericarp and/or testa and endosperms of cypselas can also be considered as taxonomically significant. Distinct differences were observed between two taxa for many characteristics. Notable among these were occurrence of stylopodium, size of cypsela (without pappus), nature of pappus, thickness of pericarp, presence or absence of ribs, layer of radially elongated cells in mesocarpic sclerenchyma ans parenchyma, presence of additional uniseriate palisade like sclerenchymatous layer in V. anthelmintica , but not in V. cinerea , testal epidermal layer, nature of endosperm layer, and crystal formation. Similarities between two taxa were also noted. Based on structural manifestations of cypsela at morpho-anatomical levels, an indented dichotomous key is provided for identification of studied taxa.
Highlights
Asteraceae is regarded as the largest family of Angiosperms comprising of more than 1,600 genera and 23,000 species of the flowering plants (Funk et al, 2009) with large number of herbal medicinal plants (Manjunatha et al, 2005; Chethan et al, 2012; Talukdar and Talukdar, 2013a; Marwat et al, 2015; Danalakshmi et al, 2013)
Cypsela and pappus morphology together with growth form, capitula size, florets, involucral bracts and leaf shapes were used in separating Anthemideae into 12 sub-tribes of Asteraceae (Bremer and Humphries, 1993)
Two different species of Vernonia are examined by light microscopic (LM) and scanning electron micrograph (SEM), namely – (i) V. anthelmintica and (ii) V. cinerea
Summary
Asteraceae is regarded as the largest family of Angiosperms comprising of more than 1,600 genera and 23,000 species of the flowering plants (Funk et al, 2009) with large number of herbal medicinal plants (Manjunatha et al, 2005; Chethan et al, 2012; Talukdar and Talukdar, 2013a; Marwat et al, 2015; Danalakshmi et al, 2013). The tribe Vernonieae was one of the original tribes, and consistently recognized in subsequent treatments within the family Asteraceae (Cronquist, 1977; Jones 1977; Bremer, 1987). Most of the species are assembled in the huge genus Vernonia, known as ironweeds in North America (Mukherjee and Nordenstam, 2004). It has two centers of distribution, one in Africa and other one in South America (Gleason, 1906). Vernonieae are notable for the frequent extreme cymose forms involving scorpioid cymes and a unique chemical vernolic acid and the tribe is probably most primitive among the tribes of the family Asteraceae (Jones, 1977; Robinson et al, 1980). A good introduction to the detailed characters of the Vernonieae with a limited scanning electron micrograph (SEM) survey of Vernonieae pollen types has been given by Robinson (2009)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call