9G 
Mr. Brown’s Observations on the 
for which I have already attempted to show that certain parts 
of the structure of a syngenesious floret are peculiarly well 
adapted. 
The circumstance, however, is not confined to Composites, but 
exists in an equally remarkable degree in Graminece . 
I have formerly considered the gluma, or what Linneus has 
termed calyx, in this family of plants, as an involucrum. 
In those genera where this gluma or involucrum contains seve¬ 
ral 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 Lolium , the expansion of the par¬ 
tial 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 com¬ 
mencing 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 vascu¬ 
lar structure of the inner valve of the perianthium ; w hich, whether 
it be considered as indicating that this part is formed of two con¬ 
fluent valves, an opinion I have elsewhere* advanced, or merely 
as a transposition 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 Composites is so striking, that it 
* In General Remarks on the Botany of New Holland. 
cannot 
