188 NATURE TEACHING!. 



Sucker. This is used botanic-ally in two 



(1) For a branch which starts underground, and 

 then conies above. (2) For a special sucking 

 apparatus by means of which some young 

 plants empty their seeds of food. 



Tendril. A thin structure, branched or not, by 

 means of which a plant climbs. Steins and leaves 

 are frequently modified to form tendrils. 



Transpiration. (Latin, Iran*, across ; spiro, I 

 breathe.) The giving off of water vapour through 

 the stomata of plants. 



Tuber. (Latin, tuber, a swelling). A thickened, 

 usually underground structure, which may be a 

 root or stem. Important as storehouses of plant 

 food. 



Variation. (Latin, variatio, a difference). Used 

 to express the tendency of living things to 

 differ to some extent from the ordinary type. 

 The differences which enable us to distinguish 

 different persons from one another are an every- 

 day illustration of variation in human beings. 



Vitality. (Latin, vitalis, of or belonging to life). 

 Seeds, for instance, are said to retain their vital- 

 ity so long as they are capable of growing when 

 placed under suitable conditions. 



