430 



HISTORY OF THE VKGETABLE KINGDOM. 



80 that seen from a distance, its appearance is 

 not unlike that of an old apple tree. Its leaves 

 are oval, coriaceous, of a dark green on the upper 

 surface, and whitish underneath. They are 

 several years without falling, and succeed each 

 other but partially. The acorns are of a long 

 oval form, almost black, with shallow cups of a 

 grayish colour, borne on pretty long footstalks. 

 It is said that the Indians foimerly extracted an 

 oil from them, which they mixed with their food; 

 and it is not improbable but that they ate them, 

 as they have not the austere taste of most other 

 acorns. In some years these nuts are very plen- 

 tiful, and they germinate so readily, that if the 

 weather is moist and rainy during the period of 

 their maturity, they begin to shoot out their 

 radicles even while still hanging on the trees. 

 The trunk of this oak is covered with a blackish 

 bark, which is hard and thick. The timber is 

 of a yellowish colour, deeper in old than in 

 young trees, and very heavy and compact. Its 

 texture is fine and close, the annual circles being 

 very near each other, evidently showing the 

 slowness of its growth. Being more durable 

 than the best white oak, it is much esteemed for 

 ship building, and is accordingly in high request 

 in all the harbours of the northern states, where 

 it is regularly imported. Its durability, when 

 kept dry, makes it useful in constructing the 

 upper parts of vessels; while its weight renders 

 it less adapted for the lower parts, unless when 

 accompanied by corresponding pins of red cedar 

 wood, which being light, and susceptible of re- 

 sisting decay under changes of wet and dry, 

 renders it a suitalile accompaniment to the oak. 



The small size of the tree does not afford tim- 

 bers of any great magnitude; but its spreading 

 branches furnish knees and other suitable parts 

 for ship building. The consumption of this 

 wood, both in the United States, and for expor- 

 tation to England, is now very considerable, and 

 has increased much of late years. From this 

 consumption, and the clearing of the islands on 

 which it chiefly grows for the production of 

 cotton, joined to the slow growth and difficulty 

 of raising the live oak, it is fast disappearing 

 from tlie country. 



The Willow Oak (q. phellos). This tree is 

 confined to the middle and southern states of 

 America. It attains the height of fifty to sixty 

 feet, with a diameter of two feet. The bark is 

 smooth and of a thick texture ; the leaves from 

 two to three inches long, and narrow and taper- 

 ing like the common willow; they are of a light 

 green colour and smooth surface. The acorns 

 are small, round, and not abundant on the trees. 

 The willow oak grows in humid situations. The 

 wood is of loose coarse texture, and is not much 

 used. 



Of the other species, described by Michaux, 

 we may shortly mention the laurel oak, or 



swamp willow oak, which attains the height ot 

 fifty to sixty feet. Its wood is very valuable, 

 and almost preferable to that of the live oak al- 

 ready described. The water oak, q. aquatica, 

 which, when full gro^vn, is about thirty feet 

 high, with leaves varying exceedingly in their 

 form. The downy black oak, q. triloba, forty 

 feet high, of very rapid growth, and well suited 

 for enclosures. The barren black oak, or black 

 jack of Virginia, q. nigra, of low growth, bear- 

 ing numerous nuts, which are excellent feeding 

 for hogs. The black, or quercitron oak, q. tinc- 

 toria, one of the largest of the American oaks, 

 and highly valuable for its timber and bark. 



The Dyer's Oak (q. infectoria), is that from 

 which the imt-gaUs of commerce are procured, 

 although the gall nut is common on almost all 

 the other species of the family. This species is 

 a shrub, seldom exceeding six feet in height, very 

 common in Asia Minor. It was first accurately 

 described by M. Olivier in his Travels, and the 

 shrub itself was introduced by him into France, 

 where it is now cultivated as a garden plant, and 

 grows well in the open air. 



The gall is a morbid excrescence produced bj' 

 the puncture of a winged insect, to which Olivier 

 has given the name of Diplolepis Oallce Tincto- 

 riee. This excrescence is of a globular form, 

 with an unequal and tuberculous surface. It is 

 developed on the young shoots of the tree, and 

 contains within it the eggs which the insect has 

 deposited. The best galls are gathered before 

 the transformation of tlie insect, because in that 

 state they are heavier, and contain more of the 

 tannin principle. When the insect has left them, 

 they are pierced from the interior to the surface. 

 The best galls come from Aleppo. The sub- 

 stance of which they are composed is peculiarly 

 astringent; of which, according to Sir Humphry 

 Davy, five hundred parts contain a hundred and 

 eighty parts of soluble matter, principally formed 

 of tannin and gallic acid. One hundred and 

 seventy- four tons of galls were imported into the 

 United Kingdom in 1827. 



The instinct by which certain insects choose 

 for the nests of their future offspring the sub- 

 stance of various vegetable bodies, is one of the 

 most curious provisions in the economy of na- 

 ture. After having pierced those bodies, they 

 deposit their eggs, which, being hatched, pro- 

 duce larvoe, that are more or less fatal to the ve- 

 getable substance to which they are attached. 

 According to Virey, an irritation is produced by 

 the introduction of these insects, that resembles 

 a tumour and inflammation in an animal body. 

 The cellular tissue swells; the parts, which were 

 naturally long, become round; and the flow of 

 liquid matter produces a change of organization, 

 from which results a complete change in the ex- 

 ternal form of the organ. In this way is the 

 gall produced. The oak-apple is an excrescence 



