野茨菰塊莖發芽不整齊，其一期作之營養生長勢強，二期作之繁殖潛力大，在1m2上單株產生之種子數為塊莖數的6,000倍，且塊莖在地表下的分布深達20cm。瓜皮草塊莖發芽整齊，其營養生長亦以一期作強，但繁殖潛力在兩期作上卻相同，單位面積產生之種子數為塊莖數的14倍，塊莖在土表下的分布較淺僅15cm。 密植下的野茨菰總生長勢較疏植者為高，但瓜皮草在等面積上之總生長勢差異不受栽植密度的影響。

In paddy field, the vegetative growth of Sagittaria trifolia was more vigorous in the first season, and reproductive potential was higher in the second season. This was also true for S. pygmaea except its reproductive potential showed the same in two seasons. The ratio of seeds and tubers produced from per plant of S. trifolia and S.pygmaea in one m2 area were 6,000 and 14, respectively. The sprouting of tubers in S. trifolia was not uniform as that of tubers in S. pygniaea. The depth of tubers formation of S. pygmaea under the soil were shallower than that of S. trifolia. The growth was more vigorous in high planting density than those in low planting density in S. trifolia. However, in S. pygmaea the total growth vigor in per m2 was nearly equal, regardless the number planted.