The frequency variations in the primary and secondary branches with cathodic prophylls were studied (Figs. 1-3). The secondary branches on the well-developed primary branches are alike to the branches themselves in the frequency distribution of cathodic prophylls, some ones at the basal part of their mother axis being excepted. However, the secondary branches on the short primary branches provided with a small number of nodes and those on the well-developed primary branches show the frequency distributions of cathodic prophylls different from each other (Fig. 5). As for this fact, it is interpreted that the prophyll position on the secondary branch axes, produced at the uppermost several nodes of a primary branch may be determined by some terminal effects of the primary branch axis.<br>The lateral branch whose third leaf is adaxial in position is found most frequently at the lower several nodes of the main axis (Table 4), as in the case of Xanthium²⁾. Phyllotaxis in the proximal portion of the primary branch (Fig. 6) is similar to that of Xanthium²⁾ in the fundamental pattern.<br>Plastochrone changes during plant development were studied in relation to the frequency variation of cathodic prophylls (Tables 2-3). The L-plastochrone and P-plastochrone are successively reduced, being attended with plant development. Each LP-plastochrone is elongated successively until a certain stage of development and then it becomes gradually reduced (Figs. 3-4). In response to the LP-plastochrone reduction, the frequency of cathodic prophylls falls also gradually.