Seombadi[Dystaenia takesimana(Nakai) Kitagawa] was discovered on Ulnung island in the sea east of Korea. Its utilization ability for livestock feed has been tested. Seombadi has very high values of crude protein, crude fat, N.F.E and palability. Especially, the annual dry matter yields obtained have been than that of orchardgrass and alfalfa by research reports of many investigators in Korea. This experiment was conducted to decide tile adequate plating densities and cutting times in Hokkaido area by using a method of ecological growth analysis. The results are summarized as follows; 1. Plant height reached almost 135㎝ at final cutting times in all planting densities. Flowering stages started from the middle of June to the end of June. Its results are 10 days later than reports from Korea. 2. Total and dry matter yields of stems were increased directly as the growth progressed. But, the dry matter yields of leaves increased until the middle of June. The plot of 25㎝ obtained the highest yield (2,200g/㎡), followed by 50㎝ (1,750g/㎡), Broadcast (1,100g/㎡) and 100㎝ (650g/㎡) plots, respectively. 3. CGR was affected by LAI during the vegetative growth stages and NAR strengthened CGR during the reproductive growth stages. Energy utilization (Eu) had a positive correlation with CGR throughout all the growth durations. SLA indicated a parameter of photosynthesis ability as with other crops. 4. Production structure of 25㎝ plot had the most available relative light intensity as compared with other planting densities. the light extinction coefficient was a 0.1920, this value was comparatively low. 5. Most available planting densities for production of dry matter yields were obtained from 25㎝ to 50㎝. Adequate cutting times may be before the flowering stages (until the middle of June) for palability by animals and chemical composition of the plant. 6. Total nitrogen concentration (g/㎡) of leaves was positively correlated with LAI as affected growth progressed. Total nitrogen concentration of leaves increased 1.01g (100㎝), 0.99g (50㎝), 1.03g (25㎝) and 0.71g/㎡ (Broadcast) with increment of LAI 1, respectively. 7. The distribution of total nitrogen concentration by the plant height (interval 20㎝), accumulated 40∼60% of the total nitrogen concentration in the 80∼120㎝ section of plant height. Generally, the total nitrogen concentration of stems became high when accompanied by high plant height.