Any account, however brief, should not omit mention of the orchids, which in the matter of insect pollination have reached the highest degree of organization. So detailed are their adaptations that each kind of flower is adapted to a particular kind of insect. The accounts given of tile various ways in which orchids attract insects and secure pollination really surpass belief, until one has actually observed some of the plants and their insects at work. Any greenhouse furnishes abundant examples of orchids, and our illustration represents one of the most common of our native orchids, the ordinary yellow Lady Slipper. In most orchid flowers there is a long tubular spur, at the bottom of which the nectar is found, which is to be reached by long probosces, such as can be found only in moths and butterflies. In Lady Slippers, however, there is a different arrangement. The flowers have a conspicuous pouch in which the nectar is secreted, and a flap overhangs the opening of the pouch. Behind the flap are the two pollen masses, between which is the stigmatic surface. A bee crowds itself away into the pouch and becomes imprisoned, and may frequently be found buzzing about uneasily. The nectar is in the bottom of the pouch, and after feeding the bee moves toward the opening overhung by the flap, and rubs itself against the stigma and then against the anthers, receiving the pollen on its back. A visit to another flower will result in rubbing some of the pollen upon the stigma, and in receiving more pollen for another flower.

One of the most remarkable cases of insect pollination is that shown by the ordinary Yucca, which is pollinated by a small moth, the plant and the moth being very dependent upon one another. The flowers of Yucca occur in very large prominent clusters, and hang like bells. In each bell-shaped flower there are six hanging stamens, and a central ovary ribbed lengthwise like a melon. At the tip of the ovary is a funnel-shaped opening, which is the stigma. During the day the moth hides quietly in the recesses of the flower, but at dusk she becomes very active. She travels down the stamens, and, resting on the open anthers, scrapes out the somewhat sticky pollen with her front legs. Holding the little mass of pollen she runs up on the ovary, stands astride of one of the furrows, pierces through the wall with her ovipositor, and deposits an egg in an ovule. After depositing several eggs, she runs to the apex of the ovary and begins to crowd the mass of pollen she has collected into the funnel-like stigma. These actions are repeated several times, until many eggs are deposited and repeated pollination has been effected. As a result of all this, the flower is pollinated and seeds are formed, which develop abundant nourishment for the moth larvae, whose eggs had been laid in the ovule. Just how the insect learned that this behavior on her part would secure food for her young is hard to imagine.

In studying any flower there are three questions that should be asked: (1) How does it hinder self-pollination?; (2) How does it secure cross-pollination?; (3) How does it discourage the visits of unsuitable insects?