Stomatal frequency was studied in five economically important but rare and endangered species of the genus Paphiopedilum, viz. P. Venustum, P. spicerianum, P. fairieanum, P. villosum and P. insigne. No stomata was found on the upper epidermis. Stomata occured only on the lower epidermis and all the species are characterised by low frequency of stomata ranging from 13.7 to 46.8 stomata per mm2 epidermal surface. Stomatal frequency was found to have highly significant negative co-relation with stomatal size. Higher the frequency, smaller the size of stomata and vice versa.
