92 
Mr. Brown’s Observations on the 
It is also known that in a compound spike, while the expansion 
of each partial spike is ascendent, that of the spikes, with relation 
to each other, is descendent; the terminal spike expanding first, 
and the others in a regular succession downwards. This order, 
indeed, admits of a greater number of exceptions than that of 
the simple spike; several of them apparently depending on the 
density or imperfect composition of the spike ; and the more 
usual deviation consisting in the expansion beginning below the 
apex, and proceeding in opposite directions from the point of 
commencement; the upper portion following the order of the 
simple, the lower that of the compound spike*. 
The simple racemus and corymbus are obviously very slight mo¬ 
difications of the spike, and in their expansion obey the same law. 
A syngenesious compound flower, or capitulum as it may be 
termed, is merely a spike with a shortened and generally de¬ 
pressed axis. In cases where this capitulum is unquestionably 
simple, the expansion of its flowers is uniformly from circum¬ 
ference to centre, or in the order of the simple spike. Where 
the capitula are disposed in a corymbus, which is their usual 
mode of combination, the order of the compound spike is ob¬ 
served ; their expansion with relation to each other being from 
centre to circumference. In their denser aggregations, whether 
forming a compound spike or head, the same order of expansion 
obtains, and it continues though the florets in each common calyx 
or involucrum should be lessened in number, or even reduced to 
unity, as in Echinops and Rolandra . 
* The most remarkable exception to the order of the compound spike exists in the com¬ 
pound umbel of Umbelliferae, of which the outer umbellulae expand somewhat earlier than 
the central; and as this order of expansion seems to extend through the whole natural 
family, Astrantia , in which the terminating umbel expands much earlier than those of the 
lateral branches, cannot be considered as having a compound umbel. 
The 
