TUBES AND SHRUBS. 387 



let out the dusty sulphur-like pollen. Shake a branch, or hit 

 it with a stick, when the male flowers are ripe. Each pollen- 

 grain has two air-bladders, which make the grain more 

 buoyant by giving it a much larger surface without much 

 extra weight. 



The male flowers fall off after the pollen is shed, so that if 

 the stem goes on producing male flowers year after year it 

 shows a tufted arrangement of the needle-bearing dwarf 

 shoots, the tufts being separated by bare parts marking the 

 former positions of the clusters of male flowers. 



Each female flower or " cone " (Fig. 155) arises in the 

 position of a lateral long shoot. Its bud grows rapidly 

 in the first year and is then nearly spherical and stands erect 

 on a short stalk. At the base of the cone there are some 

 small scales, and above these come the scale-like carpels. 

 Each carpel consists of a lower scale bearing on its upper 

 surface a larger and thicker scale ; the latter has two ovules 

 on its upper side near the base. 



While the pollen is being blown about, the axis of the 

 cone lengthens so as to separate the scales and allow the 

 pollen grains to reach the ovules. Then the stalk of the 

 cone bends down, while the scales grow larger and thicker 

 and become tightly packed together. Next year the cone 

 begins again to grow bigger and becomes egg-shaped and 

 pointed (about 2 inches long). In the third year the cone 

 dries up, the scales gape apart (starting at the top of the 

 cone), and the seeds escape. Examine cones of different 

 years. Do all the scales of a ripe cone bear seeds ? How 

 many seeds are on each scale? Note the long thin wing 

 attached to the seed, enabling it to be carried far by the 

 wind. 



The early germination of the seed has already been de- 

 scribed (Art. 88). After the cotyledons have absorbed the 

 endosperm and escaped from the seed, long needle-like 

 leaves are produced, which stand singly and directly on the 

 stem. In the second year single needles are produced at 

 first, but they gradually dwindle upwards into scales; in 

 the axils of the upper scales there arise the two-leaved 

 dwarf shoots. Thus the young Pine resembles adult Firs 

 in having the foliage-leaves borne singly and directly on the 

 stem. 



