The results of studies on the structure of vegetative organs of Stratiotes aloides L. are presented. An organographic analysis and detailed morphological and anatomical descriptions of the root system, shoot system, and inflorescences have been made. It is demonstrated that the S. aloides shoot system is characterized by high vegetative mobility. The main histological topographical complexes, their proportions, and histochemical features are determined. The shoot system of S. aloides is characterized by underdeveloped xylem. Lignification of the epidermal and exodermal cell wall is a compensatory adaptation providing additional reinforcing properties. The development of diffuse collenchyma and general aerenchymatization of S. aloides tissues are effective mechanisms of adaptations to the aquatic habitat.