452 



SPERMATOPHYTES (SEED PLANTS) 



Sporophyte. — The sporophytes of the Pines are mostly large 

 and in some cases are of huge dimensions. Some species of Pine 

 attain a height of 150 feet or more. It is characteristic of Pine 

 trees to have a main trunk and comparatively small lateral 

 branches. The main branches are usually in clusters, and in 

 some Pines, unless closely inspected, one might mistake the 

 branches to be in whorls. There is a gradual reduction in length 



of branches from below up- 

 ward, so that trees grown 

 in the open have a conical 

 shape (Fig. 400.) 



Pine leaves are needle- 

 like, and are commonly 

 borne in clusters or fascicles 

 of two, three, or five leaves, 

 the number depending upon 

 the species. Pine leaves, un- 

 like the leaves of deciduous 

 trees, ordinarily live two or 

 more years, and since only 

 some are shed each year, 

 the trees are always green. 

 Strobili. — The strobiU, 

 as in the Cycads, are of 

 two kinds — staminate and 

 ovulate {Fig. Jfil). The. 

 staminate and ovulate 

 strobili occur separately, 

 on the same trees, or on 

 different trees. 



The staminate strobili or 

 cones {Fig. 4-02) are pro- 

 duced in clusters and in the Northern states may be seen in May or 

 early June. They vary in size in different species, sometimes at- 

 taining a length of half an inch or more, but in many species they 

 are much smaller. They expand from the buds in a few days, 

 soon shed their pollen and disappear, usually persisting only a few 

 weeks. The microstrUi are borne laterally and are regarded as 

 short lateral branches with leaves modified to sporophylls. The 

 microsporophylls are closely crowded and spu-ally arranged. On 



Fig. 401. — A branch of a Pine, show- 

 ing an ovulate strobilus at a and a cluster 

 of staminate strobiK at 6. 



