Abstract
The present investigations were undertaken to study the formation and development of new shoots of the paddy perennial weed Scirpus planiculmis FR. SCHM. (“Ko-ukiyagara” in Japanese).
The results are as follows:
1. It was observed that in a paddy field S. planiculmis developed with in a year until the sixth to the seventh shoot and the distance from the original shoot to the terminal one exceeded one meter (Fig. 1).
2. The axillary buds which were formed at the base of the shoot developed into new shoots. The most basal axillary bud was formed generally on the fifth or the sixth node of the stem and began to grow rapidly when three to five foliage leaves emerged (Table 1 and Fig. 3).
3. The rhizome grew horizontally in soil in the early stage of development, subsequently the terminal part formed an aerial shoot, and after the third leaf emerged cutting off of a rhizome did not affect the shoot survival (Fig. 4 and 6).
4. Length of each rhizome was not related to the number of internodes but to the difference in the degree of internode elongation (Table 5).
5. Approximately one to three rhizomes developed from one shoot and there were fewer rhizomes on shoots developed later (Table 6).
6. It was assumed that the rhizome of S. planiculmis grew horizontally only temporarily in the first stage of its development under the effect of apical dominance (Fig. 7).
