Self Flower-Color Inheritance and Mutation in Mirabilis Jalapa L.

Mirabilis jalapa, commonly known as ((Four O’clock”’ “Sweet Marvel of Peru,” or ‘(Printoponite,” belongs to the Nyctaginaceae. This species is cultivated for the brilliant color and pleasing odor of its flowers. Due to its simplicity, the breeding behavior of the self flower colors has furnished classical material for illustrating the simple laws of inheritance. It may be shown, however, that the breeding behavior of these self flower colors is not so simple as was first implied, and that where formerly there were only a few flower-color classes recognized, now there are many. CORRENS (1902, 1904), the first to investigate this species genetically, failed in many cases to recognize and classify the flower colors correctly. His attention was chiefly directed toward an interpretation of the “yellow X white” varietal cross in which reds (red being used in a very general sense to cover a number of different shades) were obtained in the F1 and F,, but he failed to distinguish between the F, red flower-color types. The careful distinction between the color classes came with the work of MARRYAT (1909). Aided by the discovery of “recessive white” (MARRYAT’S W7), she was able to detect the genotypes of all the material used in her investigations. The “rose pink” homozygote and “light pink” heterozygote of KIERNAN and WHITE (1926) were probably the first true pinks known to genetic literature on this species. The pink so frequently referred to in text-book illustrations as resulting from a “red X white” four o’clock cross is probably not pink, but magenta (see also MARRYAT 1909, and KIERNAN and WHITE 1926). M . jalapa was introduced into Europe by the Spaniards in 1596. I t is native to Peru, as one of its common names, “Sweet Marvel of Peru,” suggests. HEIMERL (1901) found it to be native also to northern Mexico and the southern boundary of the United States. Under cultivation color varieties not known to the wild condition have occurred, and are recurring, spontaneously.