They often return to the hive with only small masses of the pollen, or none at all, in the pollen-baskets. The milkweed has the pollen grains bound up in little packets, attached to clips, which are more of a hindrance than a help to bees. The orchids also have the pollen in little masses, or pollinia, which bees can not gather. This great family is indeed of no value to beekeepers, either for pollen or nectar.
There are not far from 3000 species of plants in North America which are nectarless, but which of necessity produce pollen. They may be divided into two groups, one of which is pollinated by the wind, the other by insects. The first group is very much the larger, and contains the alders, birches, poplars, elms, oaks, hickories, walnuts, hornbeams, sweet gales, and hazelnut; the cat-tails (Fig. 4), bur-reeds, grasses, sedges, and rushes; and many homely weeds like the ragweed, Roman wormwood, pigweed, nettle, pondweed, sorrel, dock, hemp, meadow rue, and mugwort. The flowers are small, dull or green-colored, very numerous, and in the case of the trees are often crowded into cylindrical clusters called catkins. Usually the stamens and pistils are in separate flowers, which are borne on the same plant (monoecious), or on different plants (dicecious). They are all wind-pollinated, and produce immense quantities of pollen, which render many of them of great value to the apiarist.
Wherever there are forests of beeches, oaks, elms, or thickets of alder and hazelnut, or groves of nut-trees, there will be literally acres of bloom, and a dearth of pollen in spring need not be feared. Often the bees may obtain sufficient pollen from the willows and maples, and there may be no occasion for them to visit the wind-pollinated trees; but if the necessity arises they will resort to them by thousands. They have been known to seek a swamp of elms in such numbers that the roar in the beeyard was similar to that which occurs during basswood bloom. Bees also gather pollen from the staminate flowers of the date palm, which is wind-pollinated. In some parts of Europe the wind-pollinated hazelnut furnishes the first pollen in spring. It is composed of 5 per cent, of water, 30 per cent, of albuminous substances, and 60 per cent, of carbohydrates (sugar, starch). The chemical composition of the pollen of the insect-pollinated wild rose is almost identical with that of the hazelnut.
The vast forests of wind-pollinated evergreen or coniferous trees, consisting of pine, fir, spruce, cedar, and hemlock, likewise produce enormous quantities of pollen; hut they yield no nectar. The air in pine forests is filled with grains of pollen, which, slowly settling downward, powder the foliage of the trees, the grass, and the ground. The falling of such an immense number of pollen grains has given rise to the reports of sulphur showers. As the pollen of the common pine contains only 16 per cent, of albumen, and the indigestible sac or shell represents 21 per cent., it is much less valuable than the pollen of the flowering plants. The pollen of the conifers is very seldom gathered by honeybees. Large quantities of honey-dew at times cover the foliage of the evergreen trees.
The presence of honey-dew on the leaves of many wind-pollinated trees and shrubs has given rise to frequent reports that they yield nectar. The oaks have been repeatedly listed as fair honey plants, valuable for early brood-rearing. Indeed, the hickory, elm, walnut, and poplar have all been stated in various bulletins to furnish “some honey,” while the winged elm is credited with “an amber honey with a strong characteristic aroma.” In most cases these mistakes may be explained by the presence of honey-dew.
None of the grasses, sedges, or rushes, of which there are some 7000 species in the world, ever secrete nectar. To the grasses belong the edible cereals — corn, wheat, rye, barley, oats, rice, and millet. The planting of corn by the million acres renders it more important as a source of pollen than any other cultivated plant. It blooms, moreover, at a time when pollen-flowers are apt to be scarce, and honey-