Morphological and anatomical study of the fruits of four species of Stachyurus Siebold et Zucc. (Stachyuraceae)

The genus Stachyurus Siebold et Zucc. has always been considered as the only genus in the Stachyuraceae, but the systematic position of this family is complicated, since it has been included in various orders of flowering plants by vegetative and generative features. A thorough study of the fruits of representatives of the genus Stachyurus has not yet been undertaken. This work presents the results of a morphological and anatomical study of the fruits of four species of the genus Stachyurus. Morphological and anatomical studies of the fruits of representatives of the genus Stachyurus Siebold et Zucc. from the monotypic family Stachyuraceae are carried out. The fruits are considered as many-seeded 4-false-loculed paracarpous berries. A peculiarity of the fruit anatomy of the studied species Stachyurus is the lack of differentiation of the mesocarp. It is composed of layers of similar parenchymatous isodiametric cells with a row of vascular bundles in the center. The exocarp and endocarp are monolayers composed of parenchymatous rectangular cells elongated in a tangential direction. Separate mechanical tissues and various inclusions (resins, gums, etc.) were not found. Stachyurus species differ in the features of fruit surface micromorphology: type of surface ultrastructure, presence of pore-like areas in the cuticle, presence and shape of epicuticular wax. The identified carpological features of Stachyurus along with other diagnostic features can be taken into account in further systematic and phylogenetic studies of Stachyuraceae.

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