138 TEANSACTIONS OF THE ILLINOIS 



ROOTS OF PLANTS. 

 BY PROF. T. J. BUERILL, CHAMPAIGN. 



Existence. — It is M'ell understood that all agricultural plants are 

 furnished with what are called roots. Ever}' plant we cultivate in 

 our fields and gardens, or even in our green-houses and hot-beds^ 

 with the single exception of the mushroom, has true roots, without 

 which it cannot live and perform its proper and normal functions. 

 These roots have special work to perform, and ofiices peculiar to 

 themselves in the division and specialization of labor performed in 

 and by the plant as a whole. They are usually buried in the ground, 

 but sometimes occur in the open air, either in their normal connec- 

 tions, as in orchards and other epiphytes, or as outgrowths from the 

 aerial parts of the plant, like the roots from the climbing stems of 

 poison ivy and the Virginia creeper. 



But when we examine the hosts of species of the lower classes 

 of the vegetable kingdom, including the mosses, lichens, fungi and 

 algae, or sea-weeds and water slimes and scums, no true roots are 

 found. These plants of simple structure have not the specialization 

 of parts known in the higher plants, with which most people are 

 more familiar. The mosses have, hair-like growths which, to some 

 extent, resemble roots in appearance and function, but the structure 

 is sufficiently distinct. In thousands of still lower forms there is 

 nothing whatever suggestive of roots. In multitutes of these latter 

 the entire plant consists of a single cell, which performs all the 

 offices of root, stem, leaves, flowers and fruit. Here there is exceed- 

 ingly little of that specialization of parts and that division of labor 

 which distinguishes the higher vegetable structures. The simple 

 ones outnumber by far the species of flowering plants, but, being in- 

 dividually visible only by by the aid of the microscope, they are not 

 generally known even to exist, much less as to structure and parts. 

 The multitude of plants which exist without roots shows us the pos- 

 sibility of this phenomenon; yet, at the same time, the statement 

 holds unexceptionally true that all agricultural plants have long, 

 active roots, without which they cannot long perform their life func- 

 tions and furnish ourselves with the products upon which we are ab- 

 solutely dependent. 



Origin. — Every perfect seed has within it an embryo root. 

 This, in botanical language, is called the radicle. It often lies em- 

 bedded in nutritious matters stored for the use of the germinating 

 plantlet, and is always surrounded with the seed-coats, through 

 which it must forcibly burst its way when it begins its growth. In 

 a germinating seed the rootlet is usually, but not always, the first to 

 appear as cylindrical, somewhat pointed, white and smooth sprout. 



From this first root, called the primary root, after a little while 

 other roots, called secondary, appear as lateral branches. These ap- 



