96 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 weil 
adapted. : H-faetdoniteub HE ter | i 
The circumstance, however, is not confined to Compositæ, but 
exists in an equally remarkable degree in Graminee. | 
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 
glume, 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 glume, 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 tlie order having actually 
this disposition; but also with that peculiarity in the vascu- 
lar structure of the inner valve of the perianthium ; which, 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 Dipsacee and the 
single-flowered involucrum of Compositz is so striking, that it 
* In General Remarks on the Botany of New Holland, 
eannot 
= 
