It is owing to the neglect of British planters and the consequent irregularity of the home timber trade that this fine timber has been ousted from its former pre-eminence by imports of other kinds.
In writing of the common lime, I have used the scientific name, _Tilia europæa_ as conferred on it by Linnæus, rather than the more recent title of _T. vulgaris_. There seems a special reason for retaining the old name, inasmuch as Linnæus considered his own family name was derived from the linden tree.
[Illustration: ENGLISH ELM (_Ulmus campestris_)]
It is a matter of doubtful argument how many species go to compose the genus Elm--_Ulmus_--owing to the uncertainty of distinguishing true permanent species from varieties and natural hybrids. Foremost botanists have differed widely on the question; for whereas Bentham and Hooker recognised in 1887 only two true species growing naturally in the United Kingdom, Elwes and Henry describe five native species, besides nine varieties of the wych elm, as many of the English elm, and no fewer than thirteen varieties of _Ulmus nitens_, a species hitherto classed as a form of the English elm.
The distribution of the elm family is somewhat peculiar, extending all the way from Japan, through Northern China and Europe to North America, but not crossing to the Western States; nor is any species to be found south of the temperate zone, except in the mountain ranges of Southern Mexico. Of all the cities of the New World, Boston reminds the British traveller more vividly of home scenes than any other, by reason of the massive English elms which enrich the landscape. Pity it is that we cannot return the compliment by planting the beautiful white elm (_Ulmus Americana_), the glory of Washington city, for it does not take kindly to our island climate.
The elm with which we are most familiar in the North is the wych elm (_U. montana_), easily to be distinguished from the English elm by the fact that it throws up no suckers from the root, whereas the English elm hardly ever ripens seed, and propagates itself entirely by suckers which it sends out as colonists to an astonishing distance--50 yards and more. There are exceedingly few authentic records of the English elm ripening seed in Great Britain; on the other hand, the wych elm sometimes produces a prodigious crop. In the spring of 1909 this tree presented a curious appearance. The foregoing summer had been a very warm one, stimulating the wych elm to such extraordinary efforts at reproduction that, before the leaves appeared, the trees seemed to be covered with fresh young foliage, which was really the crowded leaf-like seed vessels. In June these leaf-like membranes had become dry scales, each acting as parachute to a single seed, so that, under a hot sun and a high wind, the air was full of them--so full that they actually choked the eave-gutters of my house. Each of these little monoplanes carried the potentiality of a majestic forest tree; given a suitable resting-place, any one of these minute seeds might develop into an elm like those at Darnaway, in Morayshire, which in 1882 were 95 feet high, with clean boles up to 24 feet. So great was the exhaustion following upon the abnormal seed crop of 1909 that some of my elms were crippled by it, and two or three died outright.[9]