52 HANDBOOK OF NATURE STUDY 



Prairie plants need a strong stem to withstand the force of 

 the ivind. Aquatic plants generally grow in sheltered bays 

 or in deep water, where winds and waves affect them but 

 little. Those that grow in running water float and are 

 wafted about by the current, and simply cling to the 

 bottom by their roots. Aquatic plants in their peculiar 

 environment do not need a strong, rigid stem; it would even 

 be a disadvantage to them. Can you show how ? 



Here is a handful of aquatic plants which I exposed to 

 the sun and air for a few hours ; and here you see a hand- 

 ful of prairie plants, which I exposed in the same way. 

 Notice how the water plants have shrunk and shrivelled, 

 while the others are not much the worse for the exposure. 



You know that prairie plants are often exposed to drought 

 and dry winds, and therefore have learned to endure consider- 

 able drying. Aquatic plants evaporate their moisture very 

 rapidly when taken out of the water, and shrivel so much 

 that little is left of them. 



Goldenrods, Blazing Star, Coneflower, and many others, 

 which in form remind us of Asters and Sunflowers, are 

 characteristic Prairie Flowers. When these beautiful chil- 

 dren of our boundless plains mingle their gold, silver, and 

 purple hues with the verdure of tall grasses, we are gently 

 reminded that soon nature will once more be sleeping, 

 while the " Northwester " sweeps furiously over her white- 

 blanket. 



Examine one of your flowers carefully, and you will find 

 that each head is composed of many very small flowers, 

 which grow from a common floor. This composite flower 

 is surrounded by a common calyx, which often consists of 

 many green scales or bracts. Nearly all of these plants are 

 hardy, and a light frost does not kill them. 



Plants which have such composite flowers are called 



Observations. Are the following among them? 



