60 TRUCK-FARMING AT THE SOUTH. 



is evaporated through the breathing pores, mainly of the 

 upperside of the foliage. Leaves absorb gases, and un- 

 der some circumstances moisture, from the atmosphere 

 through the stomata of their lower surface. It is not 

 necessary to discuss the chemical changes brought about 

 in the leaves, my object being merely to demonstrate 

 their great importance, and to show that whatever tends 

 to injure their health and vigor, tends to destroy the 

 plant. 



The digested sap, made available through the action of 

 the leaves for the support of the plant, descends and dis- 

 tributes its nourishment wherever it may be needed in 

 the interior of the plant. A plant, constantly deprived 

 of its leaves, could no more continue to live, than an ani- 

 mal devoid of skin with which to perspire, lungs with 

 which to breathe, and stomach with which to digest, 

 and there is no exception to this rule, which applies 

 alike to endogens as exogens. Therefore any weed may 

 be destroyed, if frequently hoed down, and some may 

 be killed if cut down only once. 



The crops of the truck-farmer, however, should be 

 kept so well stirred that most of the weeds with which he 

 has to contend are killed before they appear above the 

 ground. Two of our worst weeds, the Wormseed (Cheno- 

 podium ambrosioides, var. anthelminticum), and Dogfen- 

 nel (Eupatorium fceniculaceum) must be eradicated when 

 young, or they will become troublesome by sprouting 

 from the deep roots. Even our worst pest, 



:N"UT-GRASS COCO-GRASS ( Cyperus rotundus, 

 var. Hydra), 



can be destroyed, if constantly hoed, or plowed and 

 raked out, but owing to the depth of its growth and to 

 the abundance of nuts, each of which has several eyes, 

 to clear any considerable area by hoeing, would cost more 

 than the land would be worth. If a piece of land over- 



