OF PLANTS CALLED COMPOSITE. 277 



tains several flowers their expansion is generally ascendent, 

 or in the order of the simple spike. In a spike formed by 

 these many-flowered glumae, as that of Triticum and 

 Lolimn, the expansion of the partial spikes, with relation to 

 each other, is descendent, or in the order of the compound 

 spike \ in most cases, however, with that deviation, which I 

 have already noticed, of the expansion commencing below 

 the apex and proceeding in opposite directions. But as 

 the same descendent expansion takes place in a spike 

 formed of single-flowered glumae, it may be inferred that 

 the genuine type or most perfect form of a grass is to have 

 several flowers in its gluma or involucrum : a view not 

 only consistent with the fact of a great majority of the 

 order having actually this disposition ; but also with that 

 peculiarity in the vascular structure of the inner valve of 

 the perianthium ; which, whether it be considered as indi- 

 cating that this part is formed of two confluent valves, an 

 opinion I have elsewhere 1 advanced, or merely as a trans- 

 position of vessels in a simple valve, analogous to that in 

 the syngenesious floret, is evidently adapted to the many- 

 flowered spicula, though equally existing in that with a 

 single flower. 



The resemblance between the outer calyx of Dipsacece 

 and the single-flowered involucrum of Composite is so 

 striking, that it cannot appear very paradoxical to con- [97 

 sider them as both of the same nature. 



In Dipsaceae, however, there is no instance of the outer 

 calyx containing more than one flow T er, and the evidence 

 afforded by inflorescence on this subject is not altogether 

 satisfactory. 



In Dipsacus it has been long noticed that expansion 

 begins about the middle of the spike, and proceeds in 

 opposite directions from the point of commencement : this 

 order is evidently more analogous to that of the compound 

 than of the simple spike ; there being several instances of 

 spikes manifestly compound, where the same inversion of 

 the upper part exists. 



1 In General Kemarks on the Botany of New Holland [vol. I, p. 55]. 



