=611. Male cones, or male flowers.=—The male cones are borne in clusters as shown in fig. 339. Each compact, nearly cylindrical, or conical mass is termed a cone, or flower, and each arises in place of a long lateral branch. One of these cones is shown considerably enlarged in fig. 340. The central axis of each cone is a lateral branch, and belongs to the stem series. The stem axis of the cone can be seen in fig. 341. It is completely covered by stout, thick, scale-like outgrowths. These scales are obovate in outline, and at the inner angle of the upper end there are several rough, short spines. They are attached by their inner lower angle, which forms a short stalk or petiole, and continues through the inner face of the scale as a “midrib.” What corresponds to the lamina of the scale-like leaf bulges out on each side below and makes the bulk of the scale. These prominences on the under side are the sporangia (microsporangia). There are thus two sporangia on a sporophyll (microsporophyll). When the spores (microspores), which here are usually called pollen grains, are mature, each sporangium, or anther locule, splits down the middle as shown in fig. 342, and the spores are set free. [Illustration: Fig. 340. Staminate cone of white pine, with bud scales removed on one side.] [Illustration: Fig. 341. Section of staminate cone, showing sporangia.] [Illustration: Fig. 342. Two sporophylls removed, showing opening of sporangia.] [Illustration: Fig. 343. Pollen grain of white pine.] =612. Microspores of the pine, or pollen grains.=—A mature pollen grain of the pine is shown in fig. 343. It is a queer-looking object, possessing on two sides an air sac, formed by the upheaval of the outer coat of the spore at these two points. When the pollen is mature, the moisture dries out of the scale (or stamen, as it is often called here) while it ripens. When a limb, bearing a cluster of male cones, is jarred by the hand, or by currents of air, the split suddenly opens, and a cloud of pollen bursts out from the numerous anther locules. The pollen is thus borne on the wind and some of it falls on the female flowers. [Illustration: Fig. 344. White pine, branch with cluster of mature cones shedding the seed. A few young cones four months old are shown on branch at the left. Drawn from photograph.] [Illustration: Fig. 345. Mature cone of white pine at time of scattering of the seed, nearly natural size.]