232 



THE ANATOMY OF WOODY PLANTS 



in protective sheaths respectively known as coleoptyle and cole- 

 orhiza. The endosperm and embryo are inclosed by a covering 

 composed of the fused wall of the ovary and the integuments of 

 the ovule. On the flatter side of the seed toward which the embryo 



FIG. 173. Seed of Celastrus scattdens 



FIG. 174. Seed of 

 Pinus palustris. 



is placed a more or less prominent elevation is seen which is the 

 base of the style. 



Fig. 173 is a photomicrograph of a dicotyledonous seed. Here 

 the embryo occupies a median position and is provided with 

 two cotyledons instead of a single one. The endosperm or food 

 substance, as a result of the position of the embryo, entirely sur- 

 rounds the rudiment of the young plant. In the seed illustrated 

 the coat consists of the hardened integument, and the wall of the 

 ovary is not involved in the formation of the seminal covering. 



