138 STATE HORTICULTURAL SOCIETY. 



THE CLOVER LEAVES. 



The leaves of all clovers consist each of three leaflets raised on a stem. 

 If eaten by animals, a new blade never reappears on the tip of the leaf- 

 stem. Others from below on small branches take their places. 



In very dry weather or in cool weather the three leaflets approach each 

 other and bend over one another, huddling together. This has been 

 popularly called the sleep of plants, but it can hardly well be called sleep 

 in the sense that animals sleep. The movement is produced by the change 

 of the water in some cells in a short, cellus-like enlargement just at the 

 base of each leaflet. The advantage to the plant of the leaflets thus open- 

 ing and closing is apparent. In the hot sun, less surface is exposed to 

 injury, and in cool air the leaflets crowded together help prevent the escape 

 of heat. They crowd together for the same reason that pigs crowd together, 

 viz.: to keep each other warm. A large per cent, of the leaves of the pulse 

 family, Leguminosce, behave like the leaflets of clover. 



METHODS OF GROWTH. 



The stems of plants serve to hold the roots and leaves together, as 

 middlemen stand between producers and consumers. The stems and 

 branches of our larger herbaceous plants, shrubs, and trees spread out and 

 hold the leaves in suitable positions for their mutual benefit. 



Materials in a liquid condition pass from one part of the plant to the 

 other, but the explanation of the manner in which all this so-called " cir- 

 culation of the sap " is accomplished is too complex for a popular lecture. 

 In thin-walled, living cells the protoplasm may often be seen gliding about 

 in each cell. 



So far, we have understood that the plant grows by the multiplication 

 and enlargement of cells, finally sending forth branches, each of which is 

 essentially like every other branch on any given plant. 



After being well established, it is the plan for our higher plants, under 

 natural conditions, to reproduce themselves by seeds. In flowers there are 

 male and female organs. In Indian corn the pollen on the tassels at the 

 top of the stems is the male element, and the silk of the young ears sends 

 each a thread down to a young kernel. In flowers of apples the stamens 

 and pistils — male and female parts — are both in each flower, still these are 

 more certain of successful union when bees or other insects work about 

 them. Apples fail to set fruit, even when they blossom freely, because the 

 pollen is not well developed, or because the upper part of the pistil is not 

 perfect, or because wet weather at time of flowering prevents the effectual 

 access of the pollen to the proper place. In other cases, bad weather or 

 other cause favors the growth of some fungus which injures pistil or pollen, 

 or both. 



Plants are made of minute cells, most of which have extremely small 

 holes through their walls. In living cells is found the protoplasm which 

 goes from the older parts to the new. The old cells are dead, because the 

 protoplasm has left with its life. The cells are to be considered the home 

 of the protoplasm which moves from room to room, analagous to the 

 inmates of a fine, large mansion. 



The source of plant food, as can be seen above, consists mainly of water 

 and gases, with a very small portion from the soil. 



