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" The knowledge of the uses of leaves," says Dr. 

 Smith. " may throw some light upon that of the calyx. 

 Besides protection of the flower from external injuries, 

 which is one evident use of this part, it appears highly 

 probable, that it may often contribute to the growth and 

 strength of the stalk which supports it, as the leaves 

 do to that portion ofthe branch below them. The stalk 

 often swells considerably during the growth ofthe flow- 

 er, especially just below the calyx, becoming more 

 woody ; an alteration frequently necessary for the sup- 

 port of the ripening fruit. When the calyx falls very 

 early, as in the poppy tribe, I cannot find that the 

 flower-stalk is subsequently enlarged, nor in any man- 

 ner altered ; while in genera without number, whose 

 calyx is permanent, the stalk becomes not only more 

 woody, but often considerably thickened." 



Involucre Fig. 62. Nearly allied to the calyx are 

 those leaf-like appendages, which frequently enclose 

 the rays of the Umbel. To these leaves, botanists 

 apply the term Involucre ; and by Linnseus they were 

 regarded as a common calyx, placed at a distance from 

 the flowers. He adopted this opinion from necessity 

 rather than choice, being compelled to resort to the 

 involucre, for those characters which are usually de- 

 rived from the calyx ; but this necessity has been re- 

 moved, and the involucre now ranks as a floral leaf, 

 being restricted by some writers to the umbelliferous 

 plants, and applied by others to similar organs occurring 

 in some ofthe Cornels and Grasses. 



When the leaves arise from the base ofthe primary 

 branches ofthe umbel, they constitute the general i?i- 

 volucre, but when they arise from the base of the 

 secondary branches and enclose the partial umbels, the 

 involucre is said to be partial. In Lovage both are 



