Abstract: Isoetes sinensis Palmer is the first-class national protected wild plants, being evaluated as the most endangered level(CR). It is only distributed in the middle and lower reaches of Yangtze River. It is sensitive to environmental pollution. We continuously observed the development characteristics of root and leaf with the human engineering seedlings as material, using paraffin section method. Leaf primordium section is triangle with end gradually round. Leaf primordium is composed of dermatogen, periblem and plerome. A primary tracheid first appeared in vascular bundle central and two epigenetic tracheids nearly shaft surface on both sides of the primary tracheid consist inverted “V” word of the initial type primary xylem. The mature leaf had differentiated out epidermis and cortex. The epidermis cells have gomphosis. The cortex parts of cells crack into four lacunas which are independently of each other. Root section assumes the circular. The root mature area has differentiated out epidermis, cortex (exodermis, mesothelium, endoderm) vascular bundle. The mesothelium parts of cells crack into a complete tubular lacuna and connectionless with exodermis. The vascular bundle surrounded by endoderm section is triangular in shape. The root and leaf form structure, function and systematics were discussed.

Key words: Isoetes sinensis, root, leaf, anatomic structure