CHRISTMAS TREES 315 



Picea excelsa by botanists. We may contrast it with 

 the silver fir Abies pectinata {Sap in des Vosges of the 

 French, Silbertanne of the Germans), which we take as 

 the type of the genus Abies. In many respects the 

 silver fir looks like the spruce. In both the stem is 

 straight, reaching a height of 100 to 150 feet, 

 regularly furnished with tiers of branches from the 

 ground upwards. The leaves are needles, half an inch 

 to an inch long, which stand out from the branchlets, 

 but in the spruce they are quadrangular, green all 

 over, and arise all round the branch, whilst in the 



Fig. 34. — A thin slice across one of the foliage needles of the 

 Silver Fir. Highly magnified. It is flatter than the similar 

 slice of the needle of the spruce, r, r, The two resin canals ; 

 /, the mid-rib, in which two bundles of fibres and vessels 

 can be distinguished. — (From Veitch.) 



silver fir they are flat, grooved on the lower surface, 

 which is silver-grey in colour, and they tend to be 

 disposed right and left in two rows. Each needle 

 has a single resin canal in the spruce, but has two 

 in the silver fir, as may be easily seen by cutting 

 the needles across the length with a sharp knife 

 (Figs. 33 and 34). Each scale-like ovule-producing 

 leaf which goes to build up the ripe seed-bearing cone 

 has (as in all conifers theoretically) an outer scale, 

 called a "bract," attached to it which is very short 

 and hidden in the case of the spruce cone, but is longer 

 than the ovuliferous scale, and very obvious in the 



