1718 ARBORETUM AND FRUTICETUM. PART III. 
gined in the different species. Whoever has seen an acorn of the common 
British 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 as 
Pyrus, 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 fruit 
like the mountain ash. In short, the genus Quércus may be as easily detected 
at first sight by its fruit, as the Abiétine or the Leguminose 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 or 
stalked. In general, the oaks of Europe have stalked fruit, and the oaks of 
America sessile fruit. The fruit of most of the species attains maturity in 
one year ; but in some two years are required. In all, the vital principle is 
but of short duration; and very few acorns, of any species, will germinate 
after having been kept a year. The rate of growth of the oak is, in most 
species, considered slow; though this is not the case when it is planted on 
suitable soil. The most rapid-growing European species is the Q. Cérris; 
and of the American species, in America, the Q. alba. The highest-growing 
species of oaks belong to the groups Robur, Alb, and Cérris ; but full-grown 
trees 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 80ft.; and large American oaks, from 70 ft. to 90ft. 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 more 
than 1 ft. high when it has attained its full growth ; and the smallest American 
oak 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. pedunculata; and this 
species also appears to be of the greatest duration, both in respect to its 
life, and to its timber. In ordinary soils and situations, no species of 
oak 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. 
lanata, a native of Nepal, we have seen in a pot, bearing acorns, at the 
age of three or four years. In general, however, the oaks that attain the size 
of large trees do not produce fruit till they are between 15 and 18 years 
old. Like most other trees, the oak seldom bears an abundant crop of 
fruit for two years in succession; and it increases in productiveness with age. 
All the species of oak push up shoots from the collar when cut down, but 
only one or two species from the root. In North America, Michaux observes, 
dwarf, stoloniferous, or creeping oaks occur, the multiplied shoots of which 
cover immense tracts of land. The meadows situated in the midst of the 
forests 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 view 
of feeding their cattle on it, but to attract fawns and other animals from the 
forests. During these annual conflagrations, the trees often take fire, and 
whole 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 two 
or three feet above the ground. These miniature oaks have been found by 
travellers, who, unable otherwise to account for their appearance, have 
fancied them distinct species ; but as their acorns, when sown, Michaux ob- 
serves, “ have produced a taproot, like common acorns, without suckers or 
stoloniferous roots, it is not likely that there are any oaks in America 
which have naturally trailing stems.” (Hist. des Chénes, p. 5.) We have 
observed above, that oaks are generally considered of slow growth; but 
this chiefly applies to young plants, and as compared with the rate of growth 
of soft-wooded trees. After oaks have stood in good soil, and a suitable 
climate, 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, and 
continue to increase in size, for centuries. The life of some species of 
oak extends to upwards of 1000 years. There are some oaks in Britain 
