286 COMMON TREES AND SHRUBS 



(Fig. 188, 5) and three small flowers. Each flower consists of 

 a pistil of two carpels ; the ovary is two-celled, flattened, 

 and bears two stigmas. There is no cup, and only one ovule 

 develops. The ovary when ripe becomes a winged nutlet 

 (6). The catkin elongates as it ripens (2 f.c), and the 

 bracts with the two scales attached, as well as the winged 

 fruits, are scattered by the wind. 



Alder 



The Alder (A Inns glutinosa) (Fig. 189) is a characteristic 

 tree by stream-sides and in low-lying marshy districts, 

 where, along with Willows, it often forms a characteristic 

 thicket. It is usually a small tree, rarely more than fifty 

 feet high, and, growing from the base of the trunk, are 

 often many stool-shoots, which give it a shrub-like appear- 

 ance. On the roots large clusters of nodules grow, similar 

 in function to those found in leguminous plants. Like 

 the Birch, it is a light-demanding tree, and, when young, 

 grows rapidly and soon frees itself from the shade of its 

 neighbours. 



The bark is brownish-black and fissured, with wide scaly 

 ridges. The young branches and buds are greenish-brown 

 to red or violet, and when seen from a distance an Alder 

 thicket is often a rich purple. The longer quick-growing 

 shoots are smooth, but with conspicuous reddish lenticels, 

 and somewhat triangular in section on account of the 

 prominent decurrent leaf-bases (Fig. 189, 1 and 2 Lb). 



The buds are rather large, triangular, and distinctly 

 stalked (b) by a slight elongation of the axis beneath the 

 lowest bud-scale. The leaf-scars are ovate to rhomboid, 

 with five leaf-traces, often reduced to three by the fusion 

 of the three lower ones. The bud-scales are stipules 

 (Fig. 189, 3), coated with a waxy secretion, and are not easy 

 to separate. Note the relationship between leaves and 



