This section is from the book "The Gardener's Monthly And Horticulturist V20", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
Some remarkable discoveries have been made conjointly by Messrs. Isaac Burk, Edward Potts and Dr. J. Gibbons Hunt, of the Philadelphia Academy of Natural Sciences, and which have recently been communicated to that body. That Asclepiadaceous flowers catch insects is well known. In the common milk-weed and other allied plants portions of legs, antennae, and tongues may very often be found in the flowers. These have generally been supposed to be caught as it were by accident, through the limbs being drawn through the narrowing clefts of some of the segments. But from observations made in the Stapelia, the well-known "toad-plant" or "carrion flower " of our greenhouses, there seems to be in this genus at least a peculiar trap, which, on being touched, springs shut and catches what is put into it; and it is by this peculiar piece of mechanism that insects are caught. The wonderful discovery opens up again the question of the true relation in the great plan of Nature between flowers and insects. It is believed that an occasional cross is beneficial to a species, and that insects are the great agents by which in certain kinds of flowers foreign pollen is brought, to effect the cross. Insects should be regarded as the flowers' friends.
So long as these captures were regarded as mere accidents, one might rest satisfied with an explanation on record, offered by Professor Asa Gray, that it simply proved there was no benefit unmixed with evil in the world. But, if we find that there are in flowers traps deliberately set to catch insects, which we suppose engaged in a special design to cross-fertilize these flowers, it is impossible to conceive that these cross purposes can be both working to the one end. Dr. Hunt suggests that possibly the plant is really insectivorous, and that the insects it traps are used to nourish the flower in its efforts at producing seed. But, as only the leg or tongue is caught, and the insect, if* unable to tear its body away, remains to dry up, it is difficult to conceive just how the insect can benefit the flower. That the visits of insects are of very little use for cross-fertilization may be inferred from the fact that in Asclepiadaceous flowers freely visited by insects not one flower in a hundred perfects a seed-vessel. The great question still remains: If not for nutrition nor for cross-fertilization, what are the insects' visits for? It can scarcely be for the insects' good, when the visits terminate so disastrously to the visitors. - Independent.