1. The morphological variations of the flower and inflorescence of the following four categories of plants were observed: (1) plants grown from the seeds,which were collected from the scion of Brassica pekinensis grafted on B. oleracea; (2) plants grown from the seeds of B. pekinensis resulted from supplementary pollination with the pollens of Cheiranthus cheiri; (3) untreated plants of B. oleracea in their later growing stage (from May onward) and (4) the natural hybrids between B. oleracea and B. oler var. acephala f. tricolor.
2. Different forms of internal proliferation were found among the flowers of the plants of the first category. The single flower of an ordinary raceme may vary throngh various intermediate forms to a small raceme. It is suggested that this might be a kind of recapitulation of the phylogenetical development of the inflorescence.
3. The variations of the flowers of the plants of the three other categories are great: the petals bearing small spinous pieces along vascular bundles;the occurrence of supernumerary petals and/or stamens; the stamens being foliage-like; the noncruciform corolla and the non-tetradynamus androecium; the petals and stamens long persisting after fertilization; the pistils being fasciated, inflated, or being ellipsoidal; the ovary being apocarpous; the ovary-stalk elongated, sometimes branching and bearing under-developed pistils; a minute pistil occurring within an ovary; the ovules beingfoliaceous; and the flower reduced to a single pistil and subtended by a bract, while the former being apocarpous and foliage-like, bearing abnormal ovules.
4. The appearance of the variations of the floral organs described above were suspected to be due to the unusually prolonged vegetative period interacted with the effect of different kinds of treatment, such as: wounding, grafting, hybridization, and supplementary pollination with foreign pollens.