Material and methods
Chlorophytum laxum was collected from scrub forests of Narthamalai, Pudukottai district of Tamil Nadu, India (Fig. 1).Chlorophytum kolliensis was collected from Kolli hills, Namakkal district, Tamil Nadu (Fig. 2). The collected specimens were preserved following standard protocols. The morphological comparison was done from the herbarium deposits at MH and RHT (for herbarium acronyms, see Thiers 2017) along with relevant literature. In addition, digital specimens from online resources, such as Kew Herbarium Catalogue (http://apps.kew.org/herbcat/navigator.do) and the Plants of the World online (http://www.plantsoftheworldonline.org/) were also referred.
Sequencing of rbcL , matK and trnL-trnF regions ofChlorophytum species were done at Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram, Kerala, India. The sequences were submitted to NCBI and the accession numbers are OP028638 and OR542640. The sequences were aligned using Clustal W and phylogenetic tree was constructed using the maximum likelihood (ML) method with the following options: 1000 bootstrap replication phylogeny test, Tamura 3-Parameter Model, Gamma distributed (G) using MEGA software (Zhu et al . 2018). The T3P model was identified by jModeltest as the best fitting substitution model based on AIC and BIC criteria (Posada 2008).
Scanning Electron Microscope (Carel Zeiss, EVO-18) image of seed, anther lobe and pollen were obtained from ACIC, St.Joseph’s College, Tiruchirappalli, Tamil Nadu, India and free hand section of tuberous roots of Chlorophytum and safaranin staining were carried out at Department of Botany, St.Joseph’s College, Tiruchirappalli, Tamil Nadu, India.