MODE OF GROWTH OF WINTER WHEAT. 33 



Winter wheat is in its developement extremely like a 

 biennial plant. In the biennial turnip we see that with 

 the first leaves a corresponding number of root-fibres are 

 produced ; and that after the formation of the leaf-top, 

 the root begins to expand greatly in size and extent, 

 immediately after which the flower and seed-stalk shoots 

 forth. 



Yeiy soon after winter-wheat is sown, the young plant 

 puts forth the first leaves, which in the course of winter 

 and the early months of spring increase to a tuft ; to all 

 appearance the vegetation of the plant seems to cease for 

 weeks and months. When warm weather comes, the 

 plant puts forth a soft stem, several feet high, furnished 

 with leaves, and bearing at the top an ear set with flower- 

 buds m which, after floAvering, the seeds are formed. As 

 the seed is developed, the leaves fi'om the bottom upwards 

 tm^n yellow, and die with the stem as the seed ripens. 



It camiot be doubted that while the growth of the 

 plant appears to have ceased before .the time of shooting, 

 the over and under ground organs are in constant activity ; 

 food is incessantly absorbed, which, however, is but par- 

 tially employed to increase the mass of leaves, but not 

 to form the stem. There is, therefore, every reason to 

 believe that the far larger portion of the organisable 

 matter produced in the leaves during this period goes to 

 the roots, and that this store is afterwards applied to the 

 formation of the stalk. On the approach of warmer 

 weather all the operations of life in cereal plants are 

 quickened, and the quantity of food daily absorbed and 

 worked up increases with the extent of the absorbing and 

 elaborating organs. In spring many of the older leaves 

 and of the root-fibres die in the portions of the soil 

 exhausted by them ; the root-tops send forth new buds, 

 and with every new bud new rootlets, until the stalk- 



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