PINES 281 



606. Germination of the seed takes place when water 

 is again supplied, resulting in a resumption of the growth 

 of the embryo, the bursting of the brittle 

 integument (indusium) and the escape of 

 the root, stem and leaves of the embryo. 

 The root penetrates the soil and provides 

 water, while the leaves (now green) pro- 

 vide carbohydrates, completing the estab- 

 lishment of the new plant. F 1 1 5 8 _ 



507. There are about half a dozen genera f ^ s n ( n d P Yr n o d - 

 of Modern Pines, distinguished by their P***")- 

 leaves and cones, as follows: 



I. Twigs with primary green 

 leaves only. 



1. Cone scales persistent. 



i. Leaves prismatic, four- 

 angled. (Spruces) PICEA 

 ii. Leaves flat. 



(a) Megasporophylls (False 



long, protruding. Hemlocks) PSEUDOTSUGA 

 (6) Megasporophylls 

 short, not protrud- 

 ing. (Hemlocks) TSUGA 



2. Cone scales deciduous, the 



cone falling to pieces. (Firs) ABIES 



II. Twigs with both primary and 



secondary green leaves. 



1. Leaves evergreen. (Cedars) CEDRTJS 



2. Leaves deciduous. (Larches) LARDC 



III. Twigs with only secondary 



green leaves. (Pines) PINUS 



508. The very young twigs of the last genus (Pinus) are 

 covered with flat primary leaves which die immediately, 

 and in their axils short twiglets push out bearing five, 

 three or two very narrow leaves, the secondary leaves, 

 which are the only ones persistent on these plants. Com- 



