The Poplars are very fast-growing trees; they will shoot up to a great height in the life-time of a man, and for this reason they are often planted where a screen is quickly required. The lower part of the trunk is dark and is deeply furrowed, but the upper is a dingy yellow colour, and on it there are many black streaks. Early in March the White Poplar begins to flower. It is one of the catkin-bearing trees, and high on the upper branches there dance and dangle long slender woolly tails of a purplish red colour. These are the stamen catkins (4), and you must pick one to pieces and see how beautifully it is made. The stamens are grouped together in little bunches of from eight to thirty on a round disc, and at the foot of this disc, on one side, rises a scale which is green on the lower half and reddish brown on the upper half. This scale is deeply and irregularly toothed all round the edge, and is surrounded with fine silk which stands up like a fan. These bunches of stamens are placed all round the catkin tail, with the scales nearly covering the purple stamen heads. As soon as the pollen dust in the stamen heads is ripe and the wind has shaken it out of their dust-bags, the catkin shrivels and falls to the ground. You will find the ground strewn with them in early spring. But the White Poplar has another catkin flower which bears the seeds, and this flower grows on a separate tree. These seed catkins (3) are stouter and shorter, and are not nearly so noticeable as the long stamen catkins. The green seed-vessel sits in a tiny cup, and on the top of the seed you see a cross of four yellow rays. On one side of the cup rises a scale which is brown at the upper edge and is fringed with down as in the stamen catkin. The wind brings the stamen dust to the four yellow rays on the top of the little seed-vessel, but if there should be no stamen-bearing trees growing near, then the White Poplar can produce no new seeds; it remains barren. The leaves (2) of the White Poplar are triangular in shape and are deeply jagged all round. When in bud the sides of the leaf are rolled towards the centre, so that the under-side of the leaf, with its thick white lining, is turned outward. The young branches and buds are also thickly covered with fine white down. The Poplar leaves never seem to be still; they dance and sparkle in the sunshine, and even on quiet days you will see them fluttering. In autumn these leaves turn golden yellow before they fall. The wood of the White Poplar is too quickly grown to be very durable. It is largely used for making children’s toys, because it does not readily split when nails are driven into it. It will not burn easily, and for this reason it makes good floors for dwelling-houses.