Turning now to outgrowths of a woody nature, the well-known burrs or knaurs, so common on elms and other trees are cases in point.
In the Mountain Region at the bases of the mountains are oaks, hickories, chestnuts and white poplars: above these are hemlocks, beeches, birches, elms, ashes, maples and limes; and still higher up are spruce, white pine and balsam; and all but a comparatively few of the higher mountains are forest-clad to their summits.
New Haven is popularly known as the "City of Elms," because of the number of these trees.
Pine forests surround the town, and oaks and elms of more than a century's growth shade its streets.
On every side the town is surrounded by royal parks and woods of sycamores, plane-trees and elms, often of extraordinary size.