Notes
Leaf epidermal features such as the epidermal cell (length and width) and stomata (size) ofC. laxum is similar in the present collection as reported by Nalawade and Gurav (2017) i.e. 332±20 x 22±1.5 µm and 27.5±1.3 x 25.6±0.5 µm respectively. The features of C. kolliensis are 228.7±21 x 28.3±0.3 µm (epidermal cell) and 27.6±1.0 x 26.5±0.7 µm (stomata). Hence it is observed that the epidermal cell is longer and narrower in C. laxum when compared toC. kolliensis .
Cross sections of Chlorophytum kolliensis tuberous root display an outer rhizodermis, middle cortex and inner stele (Fig. 3). The rhizodermis is made up of one layer of radially elongated closely arranged cells. The cortex consists of ovoid or spherical parenchyma cells with intercellular spaces. Strikingly, a few calcium oxalate needle like crystals is observed. The endodermis consists of a single layer of polygonal cells that are uneven in size with prominent casberian stripes. The vascular system is characterized by 13 xylem and phloem bundles in a radial and alternative arrangement. Xylem consists of 2-4 protoxylem vessels, one or two metaxylem vessels alternated with phloem elements. Tuberous root anatomy of C. kolliensis having broader pith (approximately 14 cells across) and more number of vascular elements (13) differs from that of C. laxum that has narrowed pith (3-4 cells across) and a fewer vascular elements (8).
Seed of Chlorophytum is discoid having reticulate grove and echinate projection. The reticulate grove is deep in C. kolliensis and shallow in C. laxum (Fig. 4). Pollen grains are ellipsoid, monosulcate with reticulate exine in C. laxum and ovoid, monosulcate with reticulate exine in C. kolliensis . Size of pollen in C.laxum is 27-28 x 16-17 µm, but that ofC.kolliensis is 21-23 x 18-19.5 µm. P/E ratio is 1.6 and 1.2 respectively.
The combined data matrix of rbcL, matK and trnL-trnF has 3508 characters (rbcL-1355, matK-1510, trnL-trnF-643) in length, in which 183 variable characters are identified. The maximum likelihood tree showed two distinct clades, C. comosum, C. malabaricum and C. tuberosum as one clade and C. laxum and C. kolliensis as another clade (Fig. 5). Molecular evidence from two chloroplast loci showed C. laxum is distinct from C. kolliensis , and at least as distinct as other accepted species in the genus. The scape ofC. laxum and C. kolliensis is slender whereas it is stout in other species of Chlorophytum. Molecular markers have been used to identify different species of Chlorophytum based on RAPD and rbcL sequences (Meenu et al . 2010).