Plants in Relation to Man 



487 



Exercise. The seed of corn, peas, beans, chestnuts, and other 

 common plants should be examined for the purpose of identifying these 

 parts. The food supply enveloped in the seed covering is necessary 

 for the young plant in its early growth apart from the parent plants, 

 and before it can assimilate from the air and the soil all the materials 

 it needs. 



The value of the food supply in seeds may be demonstrated with 

 peas, beans, or corn. Cover loosely with mosquito netting a glass 

 tumbler, and fill with water to touch the netting. Prepare several 

 corn grains or other seeds by soaking in water for twenty-four hours. 

 Leave two or three grains whole, but from the others cut away all 

 the food material possible without injuring the miniature plant. 

 Place the prepared grains on the mosquito netting. Keep the netting 

 moist by adding water as needed. Observe stages in germination, 

 course of root growth and that of stems. The rate and size of growth 

 show clearly the value of the food supply in seed. 



233. Incomplete flowers. Some plants produce flowers 

 which do not have all the parts or organs named. There are 

 flowers which have both stamens and pistils but lack petals 

 or sepals or both. The flowers of the poinsettia are without 

 petals, but have a circle of brilliant red leaves which serve the 

 same purpose. Some flowers have stamens, but no pistils, 

 and others have pistils, but no 

 stamens. The flowers which have 

 stamens but not pistils are called 

 staminate, and those which have 

 pistils but not stamens, are called 

 pistillate. These two kinds of 

 flowers may be produced by the 

 same individual plant, as in the 

 corn and the squash, or by differ- 

 ent plants of the same species, as 

 in the fig, mulberry, willow, sassafras, and perhaps alders 

 and birch. 



Corn flower. The squash or cucumber plant (Fig. 153) 

 should be studied to determine which of its flowers are pistillate 

 and which staminate. One of the most interesting examples of 



FIG. 153. The staminate 

 and pistillate flowers of the 

 cucumber. (After Baillon.) 



