Journal of Heredity 25(10): 405 (1934)
The Ohio State University

IN the course of producing hybrid irises several thousands of seeds have been germinated each year for the last two or three years in the Botanic Garden at Ohio State University. Only once before was a case of twin seedlings suspected and that did not on examination prove definitely to have happened as the individuals could not be satisfactorily separated from a mass of crowded seedlings. It appears then that twinning is rather rare. Whether this pair is a two egg pair or a case of identical twins will have to wait for answer when the plants have matured and bloomed. It is expected that the difference if any will appear in the habits of growth and appearances of the flowers. The photograph shows clearly the close connection of the two plants and in the foreground are the remains of the single seed and the modified cotyledon which acts as an absorbing organ connecting the plumule and hypocotyl with the endosperm during germination and early growth stages. The plants are hybrid seedlings of the species Chaemaerisis, one of the dwarf irises of the bearded group frequently seen in gardens. Since rhizome division is the common means of propagating these irises, if these are identical twins, we have an example of precocious vegetative multiplication.

Figure 10

This pair of closely joined plants of the dwarf bearded iris arose from a single seed. At present the twins seem much alike, but not until the plants flower will it he possible to decide whether they are "identical" or "fraternal" twins. This iris is normally propagated vegetatively, and identical twinning might he considered to he a precocious manifestation of the normal reproductive tendency of the species.