There are several species of Ficus, though none of them will bear the open air in England except the common kind; and only two produce eatable fruit; viz., _F. Carica_, and _F. Sycamorus_,—the Sycamore tree of Holy Writ, which produces its small roundish fruit in clusters on the trunk and old branches, and not on the young wood, as is always the case with the common fig. The other most remarkable species are the Banyan tree (_F. indica_), the figs of which grow in pairs, and are about the size and colour of a cherry; and the branches of which send down roots, which soon become equal in size to the parent trunk, so that one tree soon becomes like a small forest; the Indian-rubber tree (_F. elastica_), the milky juice of which hardens into Caoutchouc, though this substance is also produced by other trees, particularly by the Brazilian tree _Siphonia elastica_; and the Pippul tree (_F. religiosa_). The leaves of this last tree are used in India for feeding silkworms, and it is said that this is one cause of the strong and wiry nature of the Indian silk; and the insect (_Coccus ficus_) feeds upon it and _F. elastica_, which produces the substance called lac, of which sealing-wax is made. This species takes its specific name of _religiosa_, from the legend that the Hindoo god Vishnoo was born under its branches. CHAPTER XI. THE CATKIN-BEARING TREES: ILLUSTRATED BY THE WALNUT, THE HICKORY, THE WILLOW, THE POPLAR, THE ALDER, THE BIRCH, THE OAK, THE BEECH, THE SWEET CHESTNUT, THE HAZEL, THE HORNBEAM, THE HOP HORNBEAM, THE PLANE TREES, THE LIQUIDAMBAR, MYRICA, COMPTONIA, CASUARINA, AND _Garrya elliptica_. The plants contained in this chapter are placed by modern botanists in six or seven different orders; but I have been induced to group them together, both because they follow each other in regular succession, and because there is a certain degree of general resemblance which connects them together, and renders it easier to retain their names when linked together by the association of ideas, than it would have been if they had been each described separately.