GYMNOSPERMS 



VEGETATIVE ORGANS 

 EXTERNAL CHARACTERS 



TAKE a branch of Pinus sylvestris, cut in autumn, including 

 at least four years' growth. The limits of each year's growth 

 may be recognized externally at those points where false whorls 

 of strong lateral axes are developed ; and the portion of stem 

 lying between two such whorls may be regarded as roughly 

 representing one year's growth. 



I. Consider first the growth of the year in which the branch 

 was cut, i.e. the part above the youngest whorl of lateral axes. 

 At its apex is a large bud, surrounded by a variable number of 

 smaller lateral buds. 



From a bud, which has been treated with alcohol to remove 

 the external secretion of the resin, detach some of the brown 

 scale-leaves, which cover it externally. Note 



1. The succulent base of these scales. 



2. Buds in their axils. 



In studying the growth of the current year, bear in mind 

 that it has been derived from a bud which had a similar 

 structure to that which is now seated at its apex. Examine 

 the stem of the current year externally, and note 



1. The thick main axis, more or less succulent in appear- 

 ance : its surface is marked by longitudinal grooves. 



2. The persistent brown tooth-like bases of the scale-leaves of 

 the bud, the upper part of which had fallen in spring : they are 

 best seen at the lower part of the internode. 



