Pinus (seeds, and 

 young sporo- 



PINES 281 



506. Germination of the seed takes place when water 

 is again suppUecl, resulting in a resumption of the growth 

 of the embryo, the bursting of the brittle 

 integument (indusium) and the escape of nN\\|/A 

 the root, stem and leaves of the embryo. C^^^f^ 

 The root penetrates the soil and provides C^^\ \ i 

 water, while the leaves (now green) pro- . — ^ ( 

 vide carbohj^drates, completing the estab- 

 lishment of the new plant. f i a . 1 5 s 



507. There are about half a dozen genera 

 of Modern Pines, distinguished by their ^^^^""^^ 

 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 fiat. 



(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 



H. Twigs with both primary and 

 secondary green leaves. 

 L Leaves evergreen. (Cedars) Cedrus 



2. Leaves deciduous. (Larches) Larix 



in. 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- 



