PLANT WASTES 



By Miss Alice L. Gookin. 



I 'HE losses to the plant through transpiration, exudation, 

 and in other ways is often of considerable importance. 

 Transpiration means the passing off of water from plant 

 surface in the form of water vapor. The water vapor escapes 

 only at tiny perforations in the cutin of the leaf, called stomata, 

 and through these perforations 95% of all the water a plant 

 gets is lost in the vapor state. Guttation or exudation, is the 

 loss of water in the liquid state. An observant person walking 

 in a g"arden very early in the morning after a dr}^, warm night 

 could hardly fail to notice drops of water at the ends of the 

 veins of certain leaves. This moisture is caused b}" the slow 

 oozing of a water}-^ fluid from the leaf and is known as gutta- 

 tion water. By placing a fuchsia under a bell jar, these drops 

 can be plainly seen exuding from the tips of the leaves. The 

 exudation takes place through water pores scientifically known 

 as hydathodes. These pores are larger than the stomata and 

 fewer. They are located at the ends of the side veins in 

 dicotyledons, such as the nasturtium, and at the tip of the leaf 

 of monocotyledons as in corn, wheat and grass. The drops of 

 water on grass tips on the lawn after a dry, warm night are not 

 dew^ drops, but this water of guttation. 



The hydathode, unlike the stoma, has no guard cells but is 

 a pit lined with two or three rows of living cells. In one sense 

 it is a widely open stoma beneath which is a reservoir filled 

 with water driven in by filteration. The cavity is separated 



