Fig. 1
We all know the barberry, the prickly, thorny barberry, whether with its "strings o' golden flowers" or its drooping clusters of brilliant scarlet acid berries. But each one of those berries is but a token of a bee's visit, as we shall presently see. At Fig. 1 I have shown a plan of the barberry blossom seen from below, its yellow sepals and petals open, and opposite each of the inner set, and pressed against it, a stamen. This stamen is shown below in three stages—closed, partly open, and fully open—the queer little ear-shaped lids finally drawn up, showing the pollen-pockets, and also withdrawing a portion of the pollen from the cavity. At the centre is seen the circular tip of the ovary which finally becomes the berry—that is, when the little scheme here planned has been fulfilled. This circular form represents the tip of the ovary, and the little toothed rim the stigma. Now what is the intention here expressed? This construction represents a plan, first, to invite a bee—this is done by its color, its fragrance, and its nectar, which is secreted in a gland at the base of each petal, near the centre of the flower; secondly, to make that bee bear away the pollen; thirdly, to cause that same bee to place this pollen on the stigma rim of the next flower he visits. In Fig. 2 we see how beautifully this plan is carried out by the insect, without his suspecting how perfectly he has been utilized. At A we see the same flower cut open sideways, the waiting, expectant stamens tucked away at the sides, leaving a free opening to the base of the flower. Now comes our bee. He must needs hang back downward to sip at the drooping flower. As his tongue enters, and finally touches the base of these stamens, clap! they come one after another against his tongue and face, and there deposit their load of pollen (B). The bee, who has doubtless got over his surprise at this demonstration—if, indeed, he ever had any—now flies to another blossom, perhaps on the same cluster (C). Entering it as before, the notched edge of the stigmatic rim comes in contact with the pollen on his tongue and face, and the flower is thus fertilized by pollen from another barberry blossom, the intention of the flower now perfectly realized in cross-fertilization.
Fig. 2
The seeds from cross-fertilized flowers are almost invariably more vigorous, and thus yield more vigorous plants, than those of flowers fertilized with their own pollen, and this is why most flowers have necessarily developed some means by which cross-fertilization can be secured. And this has been done through evolution working on the lines of natural selection, those seedlings which had originally happened, by a variation in the flower, to be thus favored by some chance peculiarity which insured cross-fertilization, winning in the struggle with the previous weaker individuals, and finally supplanting them altogether.
A Woolly Flock
HARDLY a season passes without my being in receipt of one or more inquiries, personal or by letter, concerning this snowy brood which haunts the alders in the swamp or along the road-side, and which envelops the smaller branches in its dense, feathery fringe. It is often one of the most frequent and conspicuous incidents in a country walk during its season, and its season ranges from its height in early summer until the frost. And yet how few there are, even of those, perhaps, who pass it every day, who have any definite idea of its character!