Varieties
The most remarkable are :—var. laciniatum, leaves deeply divided into narrow lobes; and var. tripartitum, in which the division of the leaves is carried to the midrib. Various intermediate forms, as regards the shape of the leaf, have also received names, which are not worth recognition. Variegated forms are also known in cultivation. (A.H.)
Distribution
The silver maple extends from New Brunswick through Southern Ontario to Eastern Dakota, Nebraska, Kansas, and Indian Territory on the west, and southward to Florida; but is rare near the Atlantic coast and on the higher Alleghany Mountains. Sargent gives an excellent article! on this species, with an illustration of a tree growing in the open near Boston, and says that it is an inhabitant of low sandy river banks, and grows to its greatest size on the tributaries of the lower Ohio, where it sometimes attains 120 feet in height and 9 to 12 feet in girth. Ridgway measured one in the lower Wabash Valley, which was 118 feet by 14 feet. Michaux says that near Pittsburg, trees of 12 to 15 feet in girth were common on the bank of the river, sometimes alone and sometimes mixed with the willow. Emerson states that in Massachusetts he measured a tree? 12½ feet in girth in a meadow near Northampton, and that another near Lancaster was 16 feet 8 inches round at 6 feet from the ground.
In Canada, where I saw it on the sandy banks of the Gatineau River, near Ottawa, close to its northern limit, it was no larger than in England, but the colour of the leaves was more beautiful than it ever becomes in cultivated trees with us, as is usual in the case of deciduous trees in America. In the open situations which it usually frequents, it is a wide-spreading tree ; and Michaux says that it forms a more spacious head than any other tree that he knew.
The fruit, if not destroyed by spring frost, which often happens, ripens in a few weeks after the time of flowering ; and if it falls on moist open ground, germinates at once, and sometimes produces plants nearly a foot high before winter. Sargent suggests that this rapid ripening, which is peculiar to the red and silver maples, is a provision of nature for their preservation in situations where the seed, if it ripened in autumn, like other maples, would be water-logged by floods and lose its vitality.
Sargent considers it a valuable tree for ornamental planting, only in deep moist meadow land, or by the banks of streams, where it can spread its long and graceful branches and show its brilliant foliage. This is quite borne out by the specimens which I have seen in England. It is one of the favourite trees for planting in many of the northern cities of the United States.
1 Garden and Forest, iv. 133 (1891).
2 Fifty-two years later, in 1890, we learn from a note in Garden and Forest, iii. 36, that this tree was 17 feet 4 inches in girth at the same height, having made an annual increase in girth of more than an inch, Though the trunk was partly hollow and some of the branches were gone, the tree was still growing vigorously and might live for many years more.
