"The bark, you see," continued his governess, "is very dark-colored, hard and rugged, with long, deep clefts. In smaller and younger trees it is smooth. I suppose I need not tell you that the fruit is within a burr covered with sharp, stiff bristles which are not handled with impunity. It opens by four valves more than halfway down when ripe, and contains the nuts, from one to three in number, in a downy cup. These green burrs are very ornamental to the tree; and when they are ripe, the green takes on a yellow tinge."