This paper presents phenological development of seven introduced species of the genus Crataegus L. in the Kola North. The studied hawthorn species are characterized by early onset of vegetation, short duration of linear growth of shoots and a short vegetation period. Timely completion of growth processes and lignification of shoots contribute to successful adaptation of Crataegus plants under the conditions of introduction. The authors study morphometric parameters of flowers and inflorescences, decorative qualities, size and density of the inflorescence, the number of flowers in the inflorescence, the diameter of the flowers. The most decorative species of Crataegus during flowering are selected. The plants of the studied hawthorns are characterized by the average duration of the prefloral period, annual / irregular flowering. The most decorative species during flowering are the ones with larger flowers and inflorescences: C . maximoviczii and C . dahurica . Species with a large number of flowers are characterized by a denser inflorescence. Species with smaller flowers form smaller inflorescences and vice versa. In the conditions of the Kola Subarctic, the number of flowers in the inflorescence depends mainly on the specific features. C . maximoviczii is recommended for gardening in northern cities.
CHANGES IN MORPHOMETRIC PARAMETERS OF THE DIDACNE SHELLS OF THE TRIGONOIDES GROUP IN ONTOGENESIS