Page:Wayside and Woodland Blossoms.djvu/15

Rh no less than forty-two British genera, which are divided into two series. Several of these genera will be illustrated and described in succeeding pages, but in all the flower-heads will be found to be constructed in the main after the manner of the Daisy. Some will be found to have no ray-florets, others to be composed entirely of ray-florets; and all these modifications of the type give the distinctive characters to the various genera.

In April and May in clayey meadows and pastures throughout England and Ireland the Cowslip is abundant; in Scotland rare. The flowers are of a rich yellow hue, and funnel-shaped, the five petals being joined to form a long tube. They are borne on short pedicels, a number of which spring from a long, stout, velvety stalk, three to six inches high. At the bottom of the tube is the globose ovary, surmounted by the pin-like style with the spreading stigma at the top. The five stamens are attached to the walls of the tube—in some flowers half-way down, in others at the top. In the first form the style is very long, so that the stigma comes to the top of the tube; in the second the style is short, and the stigma reaches half-way up only. The flowers are consequently termed dimorphic, and the two forms are borne on separate plants.

Though these two forms had long been known to country children as "pin-eyed" and "thrum-eyed" respectively, it remained for Charles Darwin to point out the significance of this variation, which is to ensure cross-fertilization by the visits of insects. A bee pushing its tongue to the bottom of a long-styled flower in search for honey would have its tongue dusted with pollen half-way down, and on visiting a short-styled flower some of this pollen would be sure to become detached by the sticky stigma at the same height; and vice versâ. The reader may prove this experimentally by selecting flowers of the two