Anatomical data have been used at all levels in the taxonomic hierarchy. Anatomical features have been proved to be useful in tracing evolutionary trends at the species, genus, familial and ordinal levels. Leaf anatomy has been very useful in grass systematics. The variability in the crystals present in the plant cells can be used as a taxonomically important character to differentiate between groups. Sclereids in leaves are taxonomically valuable. Fernandes and Krishnan studied the nodal anatomy along with stem anatomy of 10 species of Strobilanthes from Western Ghats. Reproductive anatomical features have been used in taxonomic studies. Data from floral and fruit anatomy usually correlated well with observed reproductive morphological features. The vasculature pattern of petal is commonly known as petal venation. Regarding the venation pattern of petal, Foster, put forward the ideas of petal architecture, which is usually with weakly reticulate vasculature that may provide some information to the evolutionary development of venation pattern in the angiosperms.