Abstract
Although red clover plants have been generally called to be biennial, there are considerable differences in their persistence among varieties, and also, among individuals even within same variety. There had been, however, a question whether persistence of red clover plants was based on the essential persistence of the primary plants themselves, or on survival done vegetatively as in white clover. To slove this question, red clover plants of the first, second, third and fourth year in ages, respectively, were observed morphologically at the end of growing season; and also, morphological and ecological observations were carried out at intervals of one or two months from the seeding year to the third year. The results were summarized as follows : 1. Tap-root of the first year plant was observed to be vital, showing yellowish white color in both internal part and surface. In the second year plant, the tap-root began to show symptoms of deterioration, being brownish in internal part and surface, where less rootlets were attached. Tap-root was in progress of deterioration in the third year plant; and then, it was internally broken down and almost disappeared in the fourth year plant (see Fig. 3-13). 2. Node-rooting at stems of the primary plant was found in most of the first year plants (see Fig. 3-A), and some of the rootlets already went into the ground, attaching some root-nodules. And these rootlets generally prolonged 10-20cm in their length at the beginning of the second year season. Secondary plantlets appeared from the nodes, most of which showed rooting already, in the second year season and thereafter. Node-rooting and appearance of the secondary plantlets were most thriving in the third year plant (see Fig. 3-E〜Fig. 4-C, which correspond to the first-fourth year plants). New node-rooting was again found at sufficiently prolonged stem of the secondary plant in the fourth year season. 3. It was observed that there were two types in appearance of the secondary plantlets. That is, one was the outer side-type consisting of plantlets, which appeared from the lower position of nodes at stems of the primary plant and grew by themselves, being detached from the primary plant, after the stems had died (see Fig. 3-C). Another was the inner side-type, plantlets of which appeared around the crown of the primary plant. and were detached from the primary plant after the crown had been broken down Fig. (3-D). The former type of plantlets were generally earlier in appearance, and consequently, more advancing in growth than the latter type of those. 4. Mechanism, of the survival maintenance done vegetatively in red clover plants was very similar physiologically and ecologically to that in white clover plants (see Fig. 4-D). More precise study on this mechanism in red clover plants must give instructive suggestions to breeding, in which there would be possibility of early-stage selection of persistent plants, and also, to pasture management.
