Abstract: The article presents the analysis of the dynamics of the Hydrangeaceae family collection in the "Fruticetum" exposition. The study was conducted on the basis of introduction cards and introduction journals of the BSI as of 2020. Currently, Hydrangeaceae includes 78 names: 6 Deutzia taxa (8 samples), 24 Hydrangea taxa (30 samples), 48 Philadelphus taxa (56 samples). Among all samples, 72.4% came in the form of seedlings, 22.3% – green cuttings, 5.3% – seeds. The main source of hydrangeas is the Main Botanical Garden of the Russian Academy of Sciences, from where 54% of all samples were obtained. Also, samples were received from other botanical gardens, nurseries and from private individuals. The oldest surviving specimen (Deutzia scabra) was received in 1974. The most intensive replenishment of the collection was observed in 1981–1983, later it slowed down. Since the mid-2000s, the attraction of new species and varieties has accelerated again. Graphs showing the dynamics of the number of taxa and samples of the studied genera are given. In total, 389 plants of the studied family grow in the exposition, of which the largest number are Mock orange. Most taxa are represented by 1 to 13 plant specimens. Further increase in the collection is constrained by the shortage of free territory for planting. This article is of interest to employees of botanical gardens, students of plant-growing directions and amateur gardeners.

Abstract: Species of the genus Philadelphus L. (mock orange) are among the most popular ornamental shrubs. They are valued for low maintenance, abundant flowering, exceptional aroma of flowers and a prolonged flowering period during high summer, by when many shrubs already fade. The results of phenological observations of 2018-2020 are presented in the article. The objects of the research were the plants of 8 cultivars of mock orange selected by N. K. Vekhov in the Botanical Garden-Institute of VSUT (Yoshkar-Ola, Mari El Republic). The vegetation of plants lasts from the beginning of May to the end of September and has a duration of 177-189 days.  The 'Airborne force' (Vozdushny desant) cultivar was characterized by the longest growing season.  The full leafing occurred in the first decade of June, the growth of scions ended in the first half of August. Flowering began in the third decade of June and lasted on average for 13-28 days. The cultivar 'Vosdushny Desant' has the earliest beginning of flowering, 'Arktika' has the latest one. The plants of 'Elbrus' were characterized by the longest flowering, 'Yunnat' – by the shortest one. There was no connection between the duration of flowering and the structure of flowers.