28 SOME FEATURES OF PLANT GROWTH. 



SEED PRODUCTION. The primary object of most farm crops is 

 the production of seed. The corn plant is familiar to most of us, 

 so we will use it to illustrate the process of seed production. 

 During the first few weeks the energy of the plant is devoted to 

 the production of leaves, roots, and stem. When these have at- 

 tained a degree of maturity, there appears at the top of the stem, 

 what is known as the tassel, which is indicated by the letter (a) in 

 Figure 31. Midway between the root and the tassel appears the 

 silk, indicated by the letter (c) in Figure 31. These constitute 

 the flower of the corn plant. At a certain period in the develop- 

 ment of these, there is given off a fine dust-like substance from ths 

 tassel. This is carried by the wind and brought in contact with 

 the silk, v^^hich is composed of many threads. These little dust- 

 like particles, or pollen grains, send out tubes v/hich pass down 

 the silk threads until they penetrate the body of the ear, (b) Fig- 

 ure 31. Here a union takes place, known as fertilization, which 

 gives rise to a kernel of corn for every thread of silk. Figure 31, 

 then, represents a partially matured ear showing how the silk 

 threads are attached to the grains or kernels. In case of other 

 cereals, such as wheat, oats or barley, fertilization is in no way 

 dependent upon the wind, as both parts of the flower are within 

 the same glume or chaff, 



ROOTS. In discussing the habits of plants it would be a grave 

 omission to omit their root development. It is the common be- 

 lief of many persons that the roots of plants occupy only the first 

 few inches of the surface soil. For the purpose of finding out the 

 extent of root development, some corn and grass plants were taken 

 from the soil with much care in order to avoid breaking the roots. 

 Figure 31 shows two hills of corn that were taken from the soil and 

 placed in a frame where the soil was afterwards washed from the 

 roots. The cut shows the root development to a depth of fifty-six 

 inches and even at this depth some of the roots were broken off, 

 showing that they penetrate to a greater depth than this. 



Figure 32 represents a bunch of Kentucky blue grass taken from 

 the soil in the same manner, which shows the root development 

 to a depth of three feet. 



But s'uch root development as is above described cannot take 

 place unless the soil is in the proper condition, and without a per- 

 fect root system, plants cannot reach their fullest development. 

 If the reader's interest has been aroused in this matter, it would 

 be well to inquire into the various conditions of the soil which has 

 so much to do with the perfect or imperfect development of plants. 



