These seed balls are very interesting. Early in spring you see them dangling in the air, and you must pluck one of the green chains and examine its round beads. In one ball are grouped together bunches of purple stamens (3), which have a few pointed, dry scales at the base of each group. As soon as these stamens are ripe and their pollen dust has been blown away, these balls shrivel and fall off. But close beside them, on a similar green chain, are dangling the seed balls (4). Inside these balls there is a soft green cushion, and all over this cushion are stuck small green seeds shaped like pears, each with a tiny point like a stalk standing up at the top. After the stamen dust has fallen on these seeds they enlarge into a small hard nut, and a tuft of bristly down grows up from the base of each seed. The ball becomes a dark brown colour, and it dangles all winter on the tree; then in spring, when the leaves are ready to burst their coverings, these brown balls fall to the ground and the dry seeds are blown away, each seed floating in the air by the aid of its bristly down. In America these Eastern and Western Plane trees are called Button trees, because the seed balls resemble old-fashioned buttons. The wood of the Oriental Plane is used by piano-makers, coach-builders, and cabinet-makers. It is a light brown colour, and is said to be very tough. PLATE XIII THE WHITE POPLAR OR ABELE TREE In the old Greek legends we read that Hercules won a victory over Kakos on Mount Aventine. On the mountain grew a thick grove of Poplar trees, and Hercules, overjoyed with his triumph, bound a branch of the graceful leaves around his brow as a sign of victory. Soon afterwards he went down into the infernal regions, the place of tears and gloom, and when he came back to earth it was seen that the upper side of his leafy garland was darkened with the smoke of Hades, but that the under-side of the leaves had been washed silver white with the sweat which streamed from his brow. Ever since that day the leaves of the Aventine Poplar grow white on the under-side, and in course of time its seeds were brought by travellers to Britain, and the tree has taken kindly to our less sunny land. So the tale runs. [Illustration: PLATE XIII THE WHITE POPLAR 1. White Poplar or Abele Tree 2. Leaf Spray 3. Seed Catkin 4. Stamen Catkin] It is by these dark green leaves with their thick white lining that you will always know the White Poplar or Abele tree (1), and when you learn how many relations it has, and how closely they resemble each other, you will be glad to have this marked distinction by which you may easily know this member of the family. The Poplar, like the Willows, prefers to grow in damp places. The most perfect trees are found in meadows close to a river. In France the people plant them along the river banks, and from far away you can trace the windings of the water by the tall Poplar spires which edge its banks.