Fig. 1. Time series of the external morphology of the terminal bud of an adult pine during one year. A, Bud burst (March); long, terminal bud subtended by three long shoot buds and one female cone developed during the previous growing season. B, Bud burst; longitudinal section of the terminal bud showing preformed tissues. Scale leaves alone or in association with a short shoot bud formed the greater part of the future growth unit. C, Shoot elongation; the lower part of the terminal bud was elongated and the short shoot buds were enlarging. D, End of shoot elongation (July); the terminal bud was small, and a lateral long shoot bud was well differentiated. Each short shoot bud had burst and bore two long needles. E, End of the growing season (October and December); the terminal bud and the axillary long shoot buds were enlarged. tb, Terminal bud; lsb, long shoot bud; ssb, short shoot bud; fc, female cone; ss, short shoot; c, scale leaf; ssbz, short shoot bud zone; cz, scale leaves with empty axils.