The variability of morphological features of inflorescences of species of the genus Spiraea L. in the conditions of Central Yakutia

The research objective was studying the variability of morphological features of inflorescences for the allocation of the most decorative types, and also the types which were of interest as raw materials. The data on the species composition of the genus Spiraea L. in Yakutia and its introduction into the Yakut Botanical Garden were presented. In total 30 species and 5 forms were tested. 14 species combined the stability with high decorative qualities and were introduced into the culture, 7 types were not promising because of low frost resistance (V-VI points). 5 species were represented by local flora and had an early and average phenological rhythm, 2 species of them (Spiraea media and S. Salicifolia) were met on natural territory of the Botanical garden. S. ussuriensis, S. media, S. dahurica, S. sericea belong to the group of spring-flowering spiraea. The studied species from other regions, S. betulifolia and S. salicifolia, had middle and late phenological rhythms and were summer-blooming. S. chamaedrifolia was distinguished among them, which occupied an intermediate position. The assessment of morphological features of inflorescences was made for 3 species differing in winter hardiness, S. S. blumie had low winter hardiness (IV points), and snow shelter was required. S. media (I point) was not damaged; one-year old shoots at S. ussuriensis (I-II points) froze slightly. The greatest number of inflorescences was noted in S. blumie, the sign variation in the species was high (31-38 %). The diameter and height of the inflorescence were more constant signs with average level of variability (V = 17-18). The most variable sign of interspecific variability were the number of inflorescences on the shoot (the coefficient of variation 33-42 %), then the diameter of the inflorescence (17-26 %) and the height of the inflorescence (17-24 %).