The white or Huntingdon willow (S. alba) is one of the most widely used European spe cies, but is little grown in America. It is a large tree, often 80 feet high, with usually short thick trunk often exceeding three feet in diameter. It is specially noted for its exceed ingly rapid growth and the large number of uses that are made of it, both ornamentally and economically. The brittle willow (S. fragilis), a native of Europe and northern Asia, becomes 50 or more feet in height and is well known in America, where it was introduced as a hedge tree about the middle of the 19th century. Stakes cut from the tree in early spring and driven in the ground will soon become trees. It is less useful than the preceding, but is popu lar for pollarding. Its twigs and smaller branches are very brittle at the point of union with the main stem, The weeping or Napo leon's willow (S. babylonica) is a native of the Caucasus, whence it has been taken to most civil ized countries throughout the world, in many of which it has become a favorite tree in cemea aeries. It has a large number of varieties. The Egyptian willow (S. agyptica) is noted for the perfumed water from its flowers in In North America the black willow (S. Nigro) is probably the best known.. It grows about 35 feet tall and is noted for its rapid disr tribtition along streasas into which its brittle twigs fall as they. arc broken ,off by every strong wind and carried far away by the cur rent before lodge and take root. Other species exhibit this trait more or less also. The pussy willow (S. discolor) is also an eastern species well known because of its silky downy catkins which appear in early spring before the leaves. It is usually a shrub, but sometimes be
comes a short-boled tree 15 or 20 feet high. Its twigs are often gathered in late winter, placed in water in a warm room or greenhouse, and the catkins thus forced into bloom. Treated in this way it is sometimes seen in florists' stores. Other well-known American species are S. lucida which grows about 12 feet tall, and the heart leaved willow (S. cordate) which grows about twice as large. Some species are popularly called in Great Britain. Of these the best known are the long-leaved sallow (S. grandifiora), gray sallow (S. cinerea), round eared sallow (S. aurita), and round-leaved sal low (S. corca).. Their chief uses are for hoops, stakes, tools, etc. They are used very little for baskets and wickerwork, since they are usually less pliable than osiers.
A very large number of insects feed upon the willow; 223 have been enumerated by Packard as found in America; in Europe 386 have been recorded. Among these are several species of plant-lice, gall-mites and scale insects. The larva of two longicorn beetles bore in the trunk and branches, and a twig-boring larva, the wil low-shoot horntail (Phyllxcus integer) bores in the twigs in which the mother deposits her eggs, and in which the pupa state is passed during the winter. The larva of the American cimbex (Cinrbex americana) which is the largest species of America saw-flies, lives upon the foliage, as do also the larva of another saw-fly, the yellow spotted willow-slug (Nematus oak trails).
Consult Bailey, 'Standard Cyclopedia of Horticulture) (New York 1916) ; Packard, 'Insects Injurious to Forest Trees' (Washing ton 1890).