66 THE BOOK OF NATURE STUDY 



and, springing from the upper surface of this near its base, a 

 wider and thicker structure which bears the ovules. These 

 two parts are known as the bract- scale and the ovuliferous scale 

 respectively. In Fig. 17, 3A, a single scale is seen from above, 

 the ovuliferous scale completely hiding the smaller bract-scale. 

 On the upper surface close to the stalk-like attachment of the 

 scale to the main stem of the cone are two large ovules, not en- 

 closed in an ovary, but freely exposed. When the little cone is 

 ready for pollination the stem lengthens slightly, thus separating 

 the scales. Some of the numerous pollen-grains in the air around 

 will enter the clefts between the scales of the cone and reach 

 the ovules. The pollen-grains in this case do not light on a 

 stigma at some distance from the ovules, but on the tip of the 

 ovule itself, which points towards the main stem of the cone. 



After pollination, which happens about the end of May, the 

 cone grows a little and the scales close tightly together again. 

 The use of the male flowers is now over, and they fall off, leaving 

 bare regions of the shoot. The pollinated cone, however, continues 

 its development, which takes a long time. By June of the next 

 season the cone has the appearance represented in the lower 

 portion of Fig. 17, 2. If a cone of this age is dissected the bract- 

 scales will no longer be distinguished, but the ovuliferous scales 

 have enlarged greatly and the two ovules are now large bodies. 

 These ovules are fertilised about this time, although pollination 

 took place more than a year previously. 



During the second summer the fertilised cone continues to 

 grow, and as it matures the scales become dry and woody. In 

 the autumn of this year or the following spring the scales separate 

 and bend back, allowing the seeds to escape (Fig. 17, 4). Each 

 seed is derived from an ovule, and carries with it when it separates 

 from the surface of the scale a thin wing which offers resistance to 

 the air and helps in the dispersion of the seeds by the wind. Fig. 

 17, 5, shows a seed and a portion of the wing. The seed is cut 

 open, and the straight embryo -plant surrounded by a white 

 mass containing reserve food can be seen enclosed in the thick 

 hard seed-coat. 



On germination the plant sends out a primary root, which 

 penetrates the soil and grows into the main root of the tree. 



