The paper presents the results of the study on fruit and seed morphology and anatomy of some chosen species of Hydrangeaceae. Fruit micromorphology, seed shape and size, seed coat pattern, testa thickness, and endosperm cells were investigated in Hydrangea heteromalla, H. paniculata, Philadelphus californicus, P. delavayi, P. incanus, P. inodorus, P. pubescens var. verrucosus, P. tenuifolius, Deutzia compacta, D. rubens, and D. scabra. Differences of potential taxonomic significance were found in the ornamentation of the fruit and the pistil surface in the Hydrangea species. The examined seeds were characterized by reticulate primary sculpture with different size and shape of the testa cells. The protrusive secondary sculpture was observed on the Hydrangea seeds. The seeds of the Philadelphus species were characterized by the rugate secondary sculpture. The seeds of the Deutzia species had sunken secondary sculpture of different patterns and these differentiations are of systematic importance. The endosperm cell walls were very thin in the Hydrangea and Philadelphus seeds, while they were evenly thick in the Deutzia seeds. That difference may be of systematic importance. The average thickness of the two-layered testa was 3.51–11.50 µm. Its inner and outer layers thickness varied from 2.27–9.25 µm and 1.24–4.05 µm, respectively. Most of the differences were found to be significant.

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