THE PINE AND OTHER CONIFERS. 



291 



which are probably necessary to prevent the attacks of 

 insects. Resin is a very characteristic product of all 

 Pines, and occurs in great quantity in the stem and 

 roots (see p. 102). 



The wood of any Conifer is much more even 

 and homogeneous in character than that of " hard " 

 or deciduous woods ; the annual rings are very distinct 



Fig. 36.— Flower of the Pine. (i) Male flowers of Pinus sylvestris. 

 (2) Stamen of Pine from in front. (3) Pollen grain. (4) Ovule-scale and covering- 

 scale of Douglas Fir to show djuble character. (5) Seeds of Douglas Fir for 

 the wing. 



and often of considerable size. There are very few 

 vessels in Pine timber. The wood is made up chiefly 

 of " tracheidsl' which are very similar in shape to the 

 cambium^ cells, and are greatly thickened. They have 

 peculiar valves on the walls, which allow the water to 

 pass easily from one to another without interfering with 

 their strengthening function, or efficiency as supporting 

 elements of the stem. There are also very numerous 

 medullary rays which pass inwards amongst these 



