The main reason is: lack of sunlight.
The lack of photosynthesis on the foliage of the plant will result in a lack of synthetic growth nutrients, the lack of plant growth nutrients directly lead to the state of the leaf is small and thin, the leaf stem is weak and small (commonly known as the "bean sprouts" plant). Calla lily leaf stem interior is porous foam structure, stem skin by a certain cross-sectional area of the porous foam structure expansion to support; leaf stem lack of photosynthetic nutrients will stem thin, porous foam wall thin, stem skin thin and lack of toughness, it is inevitably difficult to straighten.
As long as the calla lily is placed in a sunny place to cultivate, without long will change. (Note: lift into the room to enjoy not more than three days)