Макарова, О. А. Фенологический атлас растений / Н. В. Поликарпова, О. А. Макарова ; М-во природ. ресурсов и экологии Рос. Федерации, Федер. гос. бюджет. учреждение «Гос. природ. заповедник «Пасвик» ; [худож.: Хохлов В. А. ; пер.: Кислова О. С.]. - Рязань : Голос губернии, 2016.

Beginning of leaf unfolding. First leaves emerged from buds or fully expanded. As leaves begin to unfold, greenish mist on trees becomes visible from afar. Flowering onset. In goat willow flowering begins even before leaf-out; the indicator of flowering onset is stamens emerging and dehiscent an thers. In the rest of the species the indicator is opening of the first flowers. Seed and dry fru it dispersal. Spruce and pine trees shed seeds in late winter - early spring. Seeds on snow are the sign that seed dispersal has begun. In years with a long and dry autumn seeds would be shed from cones in the end of the autumn. Pine cones open on the third spring since "flowering”; subtle cracking can usually be heard in pine woods on dry and sunny days in April or early May - it is cones opening; seeds can then be seen flying. This phase in birch appears as follows: catkins with fruits have grown brown and begin to fall apart; the first open fruit catkins appear on the tree and winged seeds on the ground. 3. Trees and shrubs in autumn Observations of leaf coloration and leaf fall in trees and shrubs in au tumn are somewhat more complicated than observations on other plant development phases, but they must be done to provide knowledge about the end of the growing season (more accurately, the end of assimilatory activity in plants). The challenges here are the following-. 1. The entire tree crown rather than individual plant organs need to be monitored. 2. The transition from summer to autumn is usually more gradual than from winter to spring. Accordingly, autumn events in trees and shrubs are comparatively slow. 3. In autumn, observers have to deal with a considerable time lag in leaf coloration and fall even within the same species (phenological differentiation). Where in spring the timing of phases in individual plant specimens hardly ever differs by more than several days, in autumn, especially at the leaf coloration phase, the difference can be a week or more. It is especially pronounced in birch and willow. Autumn phenophases in plants are controlled not only by autumn weather conditions, but also by the course of development in the preced- Nature's calendars...................................................................................................................... 195