Abstract
The study was carried out on the leaf folding property of orchard grass cultivated in Morioka City. In this study the author observed the structure and development of motor cells, and measured water contents of leafblades, soil moistures and transpiration rates in the folding feature. The motor cells distributed along the midrib of the leafblade from top to base, and well developed on the lower leaves in a plant, and at the basal part in a leaf. The development of them seemed to be accelerated by light. With the seedlings, the motor cells were scarcely found on the first leaf, and developed typically on the 10th or upper leaves. The well developed motor celles were constructed of bulliform cells belonging to upper epidermis and of colorless cells originated in mesophyll. All of these cells markedly changed in their forms by folding. Under normal conditions soil moisture (% of water holding capacity) was about 44%, the leaves expanded and water contents of them were 85〜90%, but at the beginning and finishing stages of folding, the values changed to 60〜65, and about 50% respectively. Soil moistures at these times were 22.1 and 18.7%. Under more dried conditions the leaves wilted permanently and the roots died. The transpiration of orchard grass was controlled by folding, the effect was more conspicuous in the daytime than at night. The transpiration rates of folded leaves were about 70% of unfolded leaves in the whole day.
