38 



DEPARTMENT OF AGRICULTURE GEORGIA. [324] 



germination, forming two seed leaves called aicatyledonous 

 plants and whose stems increase by additions to the out 

 side exogenous plants have, at first, single descending 

 tap roots, which extend vertically into the soil. 



From these, lateral roots branch out with some regular- 

 ity, if the soil is in a finely pulverized and open condition, 

 but usually irregularly, on account of the resistance of the 

 soil. These lateral roots branch and ramify in the surface 

 soil, in search of food, which they absorb through the ten- 

 der parts of the roots proper, and the "root hairs" which 

 cluster along its sides. The tap-root seems to serve the 

 double purpose of firmly fixing the plant in the soil, and 

 of absorbing mineral food and moisture from the sub-soil. 



The upper portion of the tap- 

 root of some plants, as the carrot, 

 beet, turnip, etc., enlarge, un- 

 der cultivation, into fleshy store- 

 houses of food for the produc- 

 tion of the seed-stalk the second 

 year. They are bi-ennial plants. 

 Other plants, such as the sweet 

 potato, store the food for future 

 plants, by the enlargement of 

 their lateral roots. 



Fig. 1 represents a young di- 

 catyledonous plant at different 

 stages of its growth soon after 

 germination, illustrating the for- 

 mation of both stem and root. 



Those plants whose seeds do 

 not divide readily into two equal 

 or nearly equal parts, which put 

 forth a single leaf at germina- 

 tion, and grow from the inside monocatyledonous plants, or 

 endogens have no tap-root, but put forth a number of 



Fig. 2. 



