Аннотация:Formation of the hydrocyte system can be found very often in seed plants. In particular, during the formation of root shoots from adventitious buds in rootstock plants, in the case of natural coalescence of roots, and in different methods of shoot grafting. More strikingly it becomes apparent during regeneration; both in vivo and in vitro. The intensity of its development mainly depends on the organ morphological nature, its functional loading and to an even lesser degree on the taxonomical affiliation. Detailed analyses of the hydrocyte system at light and electron microscopical levels show its complex histological structure. It includes water-conductive elements (hydrocytes-tracheids, rarely vessel members), phloem elements (sieve cells and sieve tube members with companion cells) and tracheidal parenchyma cells. The latter accomplish functions of transferring, supporting, accumulation and storing of reserve substances. Therefore, the so-called "hydrocyte system" can be regarded as an original variety of the conductive system of seed plants.