Abstract: Mature seeds of Trapa acornis Nakai with low temperature treatment were preserved in water and would be used for germination next year. Samples of different seedling stages were photographed and collected, and prepared for observation. Anatomical study shows that the seed contains no endosperm. The two cotyledons are typically unequal in size, one of which is greatly larger than that of the other one. Anatomical structure of radicle is quite simple, while that of hypocotyl well developed. The abortion of main root makes the well-developed adventitious roots in substituting its function. The shape of seedling leaves is of four types, namely: linear, ribbon-shaped, elliptical and rhomboidal; they appear in a successive sequence. Aerenchyma is developed in all of its vegetative organs. Development of phloem is normal but that of xylem is very weak. Nutritive substances for seed germination are provided by the large cotyledon while the foliage leaves of the seedling take the second part.

Key words: Trapa acornis, Seedling, Morphological anatomy