Linnæus gave this name to this condition because it was supposed to be “monstrous,” or something opposed to law and order. Through the advance in morphological botany we have learned to regard it as the result of some normal law of development, innate to the plant, and which could as well be the regular as the occasional condition. In other words, there is no reason why Nature might not make the five-spurred flower as continuous in a wild snap-dragon as in a columbine. Many similar facts are used by those who question the Darwinian law of development.
YELLOW TOAD-FLAX.
Flower in the peloria state.
That nutrition has more to do in the evolution of form than external forces has received much aid, as a theory, from the advance during recent times of a study of the separate sexes of flowers. On coniferous trees, notably the firs, pines, and spruces, the male and female flowers are produced separately. The female, which finally yield the cones, are always borne on the most vigorous branches. When these branches have their supply of nutrition shortened and become weak, only male flowers are produced. On the other hand, branches normally weak will at times gain increased strength, and then the male flowers give female ones. This is often seen in corn fields. The generally weak tassel will have grains of corn through it. It is not infrequent to find what should normally be perfect ears on stalks weaker than usual. In these cases the upper portion of the ear will have male flowers only.
GRAINED CORN-TASSEL.
In connection with the doctrine of development, much attention has been given during the century to fertilization of flowers and the agency of insects in connection therewith. On the one hand it is contended that in all probability the flowers in the earlier periods of the world’s history had neither color nor fragrance. In this condition they were self-fertilizers, that is, were fecundated by their own pollen. In modern phraseology they were in and in breeders. When the struggle for existence became necessary, those which could get a cross with outside races became more vigorous in their progeny, and thus had an advantage in the struggle. In brief, without an occasional introduction of new blood, as it might be termed, there was danger of a race dying out. To support this view, Mr. Darwin published the result of a number of experiments. Many of them favored either side, but the average was in favor of the view that crossing was advantageous. Against this it has been urged that an average in such cases is not conclusive. If a number, though the minor number of cases, showed superiority by close breeding in his limited experiments, a new set of observations might have changed the averages, so as to make the minor figures in one instance the major in others. Again, it is contended that to increase a plant by other means than by seeds must be the closest kind of reproduction; yet some plants, coeval with the history of man, have been continued by offsets and are as strong and vigorous as ever. The Banana is an illustration. Under cultivation it produces only seedless fruits. It is raised wholly from young suckers or offsets from the roots. Mythology gives it a prominent place in the Garden of Eden, and its botanical name, Musa paradisiaca, originated in this legend.
Though much has been recorded in this line to weaken the force of the speculations that flowers late in the history of the earth developed color and sweet secretions in order to attract insects to aid in cross-fertilization, they are strongly supported by the fact that a large number of species, notably of orchids, are seldom fertilized without insect aid in pollination.
But there are anomalies even here. Some plants capture and literally eat the insects that should be regarded as their benefactors. These are classified as insectivorous plants. Some seem to catch the insects in mere sport, while in the act of conveying pollen to them. These are known as cruel plants. There are numerous illustrations of this among the families of Asclepias and Apocynum, the milk-weed family. In our gardens a Brazilian climber, Arauga, or Physianthus albens, is frequently grown for its waxy flowers and delicious odor, but the treacherous blossoms are frequently strung with the insects it has caught.