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.

Descriptions of principal plant phenophases 211 Leaf-out (end of shoot formation in herbaceous plants) is succeeded by summer vegetative development of leaves (needles). In coniferous winter annuals this phenological state is observed in both current-year needles and the needles formed in the preceding years. The size and shape of leaves/needles w ill no longer change in the course of this period. A. BEGINNING OF FLOWER BUD DEVELOPMENT International phase code BBCH 51 (Growing stage.., 2001; Meier et al., 2009) Phase description A plant has entered the phase of flower bud development (inflorescence initiation) when 10% of specimens in a transect have flower buds ready to open. Usually such flower buds are somewhat bigger than leaf buds. The nickname for this phase in w illow is ‘pussy’ willow. Further info Fenolog .rgo.ru : Flower bud development. Such buds may be slightly bigger than leaf buds. When more than a half of flower buds have opened this phase is considered at peak. Terentjeva E. Yu. (2008): Beginning of flower bud development - small green flower buds. Peak flower bud development -m ature flower buds of normal size beginning to change color. The development of flower buds is deemed to begin on the day when flower buds emerge from their sheath to become visible to the naked eye. Sinel'nikova N. V. and Pakhomov M. N. (2015): The generative cycle in most plant species begins with flower bud swelling. In wind-pollinated woody plants, male catkins begin to swell and distend, while female catkins appear later. Flower bud development begins gradually with the induction of floral primordia, and the phase onset is marked by the ap pearance of colored flower buds. In wind-pollinated woody plants, anthers are separated in male catkins, and in coniferous plants there separate male ‘cones' (microstrobili).