[Morphological and histological studies of the Chinese drug lao-guan-cao]

Lao-guan-cao has long been used in Chinese traditional medicine. It is used as an antirheumatic and circulation promoting drug for the treatment of acute and chronic rheumatalgia; also used as a detoxicant for enteritis and bacillary dysentery. The dried aerial parts of Erodium stephanianum Willd. and Geranium wilfordii Maxim. (family Geraniaceae) have been specified in the Chinese Pharmacopoeia (1990 ed.) According to the literature and the authors' market investigations, the commercial drug Lao-guan-cao chiefly consists of the aerial parts of Erodium stephanianum Willd. Also those rather popularly used in several provinces are the aerial parts of Geranium nepalense Sweet and G. sibiricum L. In this paper, the morphological and histological characters of the crude drugs derived from E. stephanianum Willd., G.nepalense Sweet and G.sibiricum L. are described. It is found that the following characters are useful for distinguishing the drugs derived from the above mentioned three species. (1) The shape and size of leaf; (2) the number and arrangement of the vascular bundles of stem; (3) the number of the vascular bundles in midrib and layers of palisade cells of leaf; (4) the presence or absence of stomata in upper epidermis; (5) the characters of cells containing crystals in sepal; (6) the characters of epidermis cells, cells containing crystals and fibers of pericarp; (7) the types of hairs and glandular hairs on epidermis of stem, leaf, sepal and pericarp; (8) the characters of anticlinal walls of epidermal cells of seed coat.