- 7 - green understorey, lianas (Hedera colchica, H.helix, Smilax ex- celsa, the rare in the Garden Clematis vitalba; Lonicera caprifo- lium, Periploca graeca, Humulus lupulus, etc.) and rich layer of evergreen ferns; Colchic forest has poor composition of the cano- py levels, poorly differentiated strata in the tree canopy, a low number of dominant trees, and a complete absence of broad-leaved evergreen species in the overstorey which consists only of deci- duous species in common with other parts of the Caucasus. Never- theless, due to the high humidity, absence of low temperatures in winter time, and less sharp seasonal contrasts, seasonal develop- ment of the whole vegetation is also rather even, although the vital activities of each species are coordinated with the sea- sons. According to Richards, this phenomenon is typical for tro- pical forest, too. A subtropical feature of the Colchic forest is that the trees and shrubs vegetate for a fairly long period and this pro- duces a longer period of flowering and fruiting (Vaccinium arcto- staphylos, Frangula alnus, Rhododendron ponticum, Daphne pontica, Laurocerasus officinalis). These processes slow down only during the period of intense growth of new shoots. Vegetative shoots in many species show sometimes two periods of growth per year; flo- wering and fruiting can continue in winter, but the growth of shoots in evergreen plants renews at the beginning of summer,sin- chronously with the fall of hibernating leaves, and in deciduous plants mainly in spring. Our northern subtropics differ sharply from those farther south by the fact that trees and shrubs do not remain green throughout the year, in contrast to the herbaceous cover; though its separate elements have a green foliage during quite definite seasons. In winter and in spring the herbaceous cover is green from vegetating European and local Caucasian species (Agrostis gi- gantea, Poa trivialis, Poa annua, Festuca drimeia, Carex divulsa, C.pendula, Epimedium pubigerum, Trachystemon orientale and others); in summer and in autumn adventive subtropical species determine the aspect of the herbaceous cover (Microstegium,Paspal- lum, Miscanthus, many spp. of Compositae, ect.). The herbaceous cover of the forest part of the Garden is not