1718

ARBORETUM AND FRUTICETUM.

PART III.

gined in the different species. Whoever has seen an acorn of the commonBritish oak would be at no loss to detect an oak of any species whatever,provided he saw its fruit; whereas in the case of many genera, such asPy rus, for example, no man, not a botanist, who had seen an apple or a pear,would recognise as species of the same genus those trees which bore fruitlike the mountain ash. In short, the genus Quercus may be as easily detectedat first sight by its fruit, as the vlbietinse or the Leguminosce are by theirs.The acorns of different species differ chiefly in the largeness or smallness,roughness or smoothness, of their calyx, or cup; and in their being sessile orstalked. In general, the oaks of Europe have stalked fruit, and the oaks ofAmerica sessile fruit. The fruit of most of the species attains maturity inone year; but in some two years are required. In all, the vital principle isbut of short duration; and very few acorns, of any species, will germinateafter having been kept a year. The rate of growth of the oak is, in mostspecies, considered slow; though this is not the case when it is planted onsuitable soil. The most rapid-growing European species is the Q. Cerris;and of the American species, in America, the Q. alba. The highest-growingspecies of oaks belong to the groups Pobur, A'lbm, and 6’erris ; but full-growntrees belonging to these groups, which have reached 100 ft. in height, are rare.The general height of what are considered large British oaks varies from 60 ft.to 80 ft.; and large American oaks, from 70 ft. to 90 ft. The smallest Eu-ropean oak is the Q. humilis, which is seldom found higher than 3 ft. or 4 ft.,and, according to Marquis, is often in the Landes, near Bordeaux, not morethan 1 ft. high when it has attained its full growth ; and the smallest Americanoak is Q. pumila, which is seldom, if ever, higher than 20 in. in a wild state.The oak which attains the greatest magnitude is Q. pedunculate; and thisspecies also appears to be of the greatest duration, both in respect to itslife, and to its timber. In ordinary soils and situations, no species ofoak attains to maturity in much less time than a century. There are, also,few trees which, when raised from seed, are so long in producing fruit;though there are some exceptions among the European oaks; and Q.Ianata, a native of Nepal, we have seen in a pot, bearing acorns, at theage of three or four years. In general, however, the oaks that attain the sizeof large trees do not produce fruit till they are between 15 and 18 yearsold. Like most other trees, the oak seldom bears an abundant crop offruit for two years in succession; and it increases in productiveness with age.All the spacies of oak push up shoots from the collar when cut down, butonly one or two species from the root. In North America, Michaux observes,dwarf, stoloniferous, or creeping oaks occur, the multiplied shoots of whichcover immense tracts of land. The meadows situated in the midst of theforests of America are burned annually, either by the Indians or the settlers ;who endeavour by this practice to produce a new herbage, not only with a viewof feeding their cattle on it, but to attract fawns and other animals from theforests. During these annual conflagrations, the trees often take fire, andwhole tracts of forest are destroyed. The roots of the trees, however,generally remain uninjured; and those of the oaks, which spread hori-zontally, frequently send up shoots which produce acorns, when only twoor three feet above the ground. These miniature oaks have been found by-travellers, who, unable otherwise to account for their appearance, havefancied them distinct species ; but as their acorns, when sown, Michaux ob-serves, “ have produced a taproot, like common acorns, without suckers orstoloniferous roots, it is not likely that there are any oaks in Americawhich have naturally trailing stems.” (Hist, des Chenes, p. 5.) We haveobserved above, that oaks are generally considered of slow growth ; butthis chiefly applies to young plants, and as compared with the rate of growthof soft-wooded trees. After oaks have stood in good soil, and a suitableclimate, for five or six years, they grow with rapidity till they have at-tained the age of 30 or 40 years, after which, most of the species live, andcontinue to increase in size, for centuries. The life of some species ofoak extends to upwards of 1000 years. There are some oaks in Britain