THE CONIFERS 181 



times on separate plants. The flowers, in the majority 

 of the Conifers, are cones consisting of scales (modified 

 leaves) aggregated on a central axis; the scales of the 

 male flowers bear pollen -sacs (microsporangia), and 

 the ovules (megasporangia) occur naked on the scales 

 of the female flowers. Resin is usually present in 

 abundance in the various parts of the plant. 



The Spruce Fir, Picea excelsa, frequently used as 

 a Christmas tree, exhibits the typical features of the 

 cone-bearing plants. It has been introduced into 

 Britain, where it is not indigenous. It is a forest 

 tree with a vertical stem, often over 100 feet in height; 

 it occurs at a great elevation on the Alps, and abounds 

 in Northern Europe. The branches reach out horizon- 

 tally, or with a slight downward slope, from the stem. 

 The leaves are needle-shaped, crowded and arranged 

 spirally. The tree is pyramidal in form, and ever- 

 green. Male and female cones (Fig. 60) are borne 

 on the same tree. As will be seen in B, the male cones 

 grow in the axils of the leaves of a shoot, the latter having 

 been formed a year prior to the appearance of these 

 flowers. The cone is shortly stalked, and its lower part 

 is composed of small, bright-green vegetative leaves, 

 termed " bracteoles "; the stamens are arranged spirally 

 on the axis above the bracteoles. They are leaf-like, 

 bright-red, and each bears two pollen sacs on its under 

 surface. The female cones (Fig. 60, A) are borne at 

 the ends of twigs, when they open their colour is red, and 

 they are between 1 and 2 inches long ; at that time they 

 are erect, but at a later stage they hang downwards, 

 evidently with a view to the easier liberation of the seeds, 

 after which they fall to pieces. In a female cone 



