**8. Ergastic crystals and medicinal raw drug identification**

Correct taxonomic identification of plants is most important before proceeding to any analytical procedure and utilization. Comparative approach on morphological and anatomical features provides distinguishable features for species to species, which is well established in identification of some medicinally useful plants [19]. Morphological features of vegetative parts with qualitative value vary with respect to habitat change and growing regions when cultivars are considered. As flowers fruits and seeds are produced seasonally and when the economically important part is leaves rhizome, corm or tuber identification based on reliable anatomical characteristics may be useful for making differentiation. Ergastic crystals can serve as an important diagnostic tool for the identification of economically important species. Presence of characteristic cuboidal ergastic crystal in the leaves of several plant species including *Costus speciosus* has been well reported [1, 55]. Cuboidal crystals of calcium oxalate are present in the mesophyll cells of *Costus speciosus* and are not reported in mesophyll cell of *Costus pictus* leaves, it can become a consistent and easily identifiable characteristic between these two species. Calcium oxalate crystal is smaller in size towards the tip of the aerial shoot in *Costus pictus* but bigger towards the base of the aerial stem. The crystal size in underground rhizome was found comparatively bigger than those in aerial shoot [19]. So the presence of ergastic crystals from various plant parts, its size and structure is an important taxonomic key for the making difference between medicinally important species *Costus pictus* and *Costus speciosus.*
