Abstract:
Apocynaceae Juss. (The Angiosperm Phylogeny Group, 2016) commonly called as the dogbane family, comprises 357 genera and about 5100 species (Nazar et al., 2013) of flowering plants including herbaceous or shrubby climbers (Wong et al., 2013; Chan et al., 2016: Lu et al., 2014). The Calotropis (Wara, hela-wara in Sinhala and errukalai, manakkovi, mannakovi, urkkovi in Tamil) which is a small genus belongs to this family consisting of two species, Calotropis gigantea (L.) R. Br. and C. procera (Aiton) Dryand. Calotropis is a succulent and xerophytic shrub or small laticiferous tree up to 2.5 m, commonly known as “milkweed” or “Crown flower” (Kumar et al., 2011; Hindi, 2013; Wong et al., 2013; Muriira et al., 2015; Moustafa and Sarah, 2017). The stem usually simple and branched at the base, woody covered with a corky bark, leaves simple, opposite, sub-sessile, white and purple-colored flowers and not scented (Sharma, 2011; Joseph et al., 2013). Inflorescence is a dense, multi-flowered, umbellate cyme, highly cross-pollinated through insects such as monarch butterflies, simple, follicle fruit (Endress et al., 2007; Joseph et al., 2013). Following figure shows the purple and white colored flowers and follicle fruit of Calotropis found in Sri Lanka. Calotropis species are most diverse in tropical and subtropical parts of Asia and South East Asia (Bangladesh, Cambodia, Burma, China, India, Indonesia, Malaysia, Pakistan, Philippines, Sri Lanka and Thailand) and extend into temperate areas (Nasser et al., 2012; Nazar et al., 2013).
