Abstract: A large numar of plantlets were obtained from cotyledon explants of Sophom japonica L. cultured in vitro. They could be classified into 3 kinds according to their morphological characteristics, viz. the normal plantlets, the hyperhydric planfiets,and the intermediate state between the two or the sub-hyperhydric type. The free water content was more than 79% in the hyperhydric shoots,and 70% in the sub-hyperhydric shoots,while less than 50% in the normal shoots. The surface anatomy of normal, sub-hyperhydric and hyperhydric stems and leaves of the plantlets were compared by scanning electron microscopy. The surface structure of the normal plantlets was similar to those found in field-grown plants,but great change occurred in that of hyperhydric and the sub-hyperhydric plantlets. The stems and leaves surface of the hyperhydric and sub-hyperhydric plantlets appeared to be uneven, wrinkled, brittle and translucent and besides the leaves were thick, curled with a reduced surface area. There was little or no epicuticular wax on the surface of epidermal cells which had irregular shapes and patterns. All leaves were amphistomatic and the stomatal density, size and degree of opening were obviously bigger in the sub-hyperhydric and hyperhydric leaves than in the normal ones. Normal stomata had kidney-shaped guard cells and resembled closely those found in the feild-grown plants, whereas abnormal stomata had deformed guard cells. All of the morphological characteristics mentioned above indicated that the sub-hyperhydric and hyperhydric shoots bended to lose their water easily and resulted in desiccation, which might be one of the major causes of failure to transfer sub-hyperhydric and hyperhydric plantlets to soil.

Key words: Sophora japonica, Tissue culture, Hyperhydric shoot, Morphological study