89 



attain tree-size are usually found near buildings and have been in- 

 troduced. 



The Willows produce wood which is light, soft, not durable, and 

 weak. It is of little commercial importance. The value of the Wil- 

 lows lies in the shoots or rods which are used in the manufacture of 

 baskets and furniture. Some reach a large enough size to be used 

 lor saw lumber but the trunks are usually of a poor shape and also 

 begin early to decay in the center. They are valuable to bind the 

 border of streams by means of their interlacing roots and thus pre- 

 vent erosion. They may also be used to prevent the movement of 

 shifting sands. 



Few trees possess such a tenacious vitality as the Willows. They 

 live a long time after they appear to be dying and repair broken parts 

 very readily and often replace them with new growth. They repro- 

 duce freely by means of sprouts, cuttings, and seeds. On very wet 

 situations, like islands or the borders of streams, they often form 

 dense thickets to the exclusion of almost all other growths. 



The Willows as a group are easily recognized even by a layman. 

 They have a characteristic external appearance which one can soon 

 learn to appreciate. It is, however, difficult to distinguish the 

 different Willows from each other. They sport and hybridize freely. 

 Very often one leaves a Willow in despair because of the fact that it 

 was impossible to identify it. Only 4 of the 15 or 20 Willows found 

 in Pennsylvania are described below because many of them are mere 

 shrubs and others have been introduced from the eastern hemis- 

 phere. The Weeping Willow (Salix babylonica L.) (Fig. 37) is very 

 common in cultivation and in some localities it has escaped cultiva- 

 tion. It can readily be distinguished by its drooping branches. The 

 Crack Willow (Salix fragilis L.) is a native of Europe. It is com- 

 mon along our streams where it reaches a large tree-size. The lat- 

 eral branches are very brittle and after a windstorm the ground 

 around the tree is usually covered with branchlets which have cracked 

 off, whence the name Crack Willow. 



KEY TO THE SPECIES.* 



Page. 

 1. Leaves persistently hairy at least beneath, S. rostrata 93 



1. Leaves smooth or nearly so when mature, 2 



2. Large tree; leaves narrowly lanceolate S. nigra 90 



2. Shrub or small tree rarely 20 feet tall; ^aves broadly lanceolate 3 



3. Capsules pubescent; petioles and stipules not glandular; buds large S. discolor 92 



3. Capsules glabrous; petioles and stipules glandular; buds small, S. lucida 91 



*It is not intended that this key will enable one to distinguish all the species of Willow found in 

 Pennsylvania. It simply aims to point out the distinguishing characteristics of the four species 

 which are described here. Other species may be distinguished by the use of Porter's Flora of 

 Pennsylvania. 



