40 ELEMENTS OF FARM PRACTICE 



500 lbs. of moisture must pass through a plant to produce 

 one pound of dry matter in the plant. This water must 

 all be given off into the air by the leaves, hence the need 

 of so many leaves. A tree, or a plant, usually has a very 

 large leaf area exposed. It is interesting to estimate this 

 leaf area on various plants,, by counting the leaves on a 

 part of the plant, measuring the size of an average leaf 

 and then computing the total, remembering that there are 

 two sides to each leaf. Each leaf has many little openings 

 or pores on its under surface through which air is taken 

 into the leaf and moisture and oxygen given off. 



Flowers are borne on the stems of plants. Their func- 

 tion is to start and develop the seed which enables the 

 plant to reproduce itself. In fact, the production of seed 

 seems to be the function of the whole plant, but it is the 

 blossom that starts the seed and as soon as the seed is 

 started the blossom falls. 



Questions: 



1. Name the four principal parts of a plant. 



2. Name at least two plants in which the edible part comes 

 from the roots. From the stem? From the leaves? From the seed? 



3. Tell the principal uses to plants of roots and leaves. 

 Arithmetic: 



1. If 400 lbs. of water are given off (transpired) by clover plants 

 to produce 1 lb. of dry matter, how many pounds will be transpired 

 from an acre of clover yielding 3 tons of hay containing 85% of dry 

 matter? 



2. Count the leavesi on an average sized hill of potatoes Meas- 

 ure an average sized leaf and find the total leaf surface exposed per 

 hill. Per acre. If a potato plant is not available, use a geranium 

 plant instead. 



GOOD SEED 



Importance. — We must have good kernels of grain from 

 which to raise a good crop, just as we must have good 

 cows from which to raise good calves. One of the 

 laws of Nature which we must consider in raising plants 

 and animals is that 'Tike produces like." If we want to 

 raise large horses we must have large horses from which 

 to raise them. If we want to raise dairy cows we must 

 keep dairy cows or cows which have the ability to produce 

 large amounts of milk. Likewise, if we wish to produce 

 good plants, we must sow good seed. There are small, 



