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EVOLUTION OF THE INFLORESCENCE. 559 
owing to the connecting links no longer existing : even then some evidence 
may be forthcoming from a minute examination of the apex of the inflor- . 
escence, a few small leaf-structures in this region without flower-buds in their 
axils may represent the aborted vegetative prolongation. 
A raceme, for example, using the term in the strictly descriptive sense, 
without regard to its origin, may then arise in two different ways, either 
from a eymose inflorescence with the panicle as intermediary, or from an 
interealary inflorescence through the loss of the vegetative continuation. 
Taking into consideration the views just expressed as regards the 
evolution of the intercalary inflorescence, it may have become apparent. that 
this type of flower-cluster must be looked upon as quite different in nature 
from all other kinds of inflorescences dealt with in this paper and traced 
back to simple eymose groupings. The former inflorescence is derived by 
the coming together, through internodal compression and loss of foliage, of 
a number of single flowers (or of simple eymose groupings of flowers) borne 
terminally on leafy shoots. While each of the latter is considered to be 
derived from a single terminal flower through the addition of lateral 
flowers produced from the leaf-axils immediately below. In fact, instead 
of all the reproduetive material being utilised in the formation of the single 
terminal flos er, it is, as it were, divided among several, new flower-buds 
being pushed from the leaf-axils below for the purpose. 
The first is a flower aggregate arising from the bringing together of 
originally separate flowers. The second is a cluster due to the production 
of flowers, in addition to the original solitary terminal one, which previously 
did not exist. 
Upon these views, then, a cymose derived inflorescence is the equivalent 
only of a single flower, or-of a single lateral flower-group, of an intercalary 
inflorescence. 
SUMMARY *. 
(1) From a comparative study it seems highly probable that flowers were 
originally borne on the plant singly, each terminal to a leafy shoot. Several 
genera and species, chiefly in those families which for other reasons may 
be considered primitive, retain for the most part this early and simple 
arrangement, e. v., Magnolia, Liriodendron ; Calycanthus ; Paonia, Trollius, 
Adonis; Papaver, Romneya; Kerria, spp. of Pyrus, Rubus, and Rosa. 
(2) From such a shoot (or shoots) bearing foliage leaves below and ending in 
ua single terminal flower, all inflorescences, as well as the solitary axillary flower, 
have probably arisen. 
* The conclusions drawn and opinions expressed in this summary apply especially to the 
Dicotyledons; at any rate the evidence is derived solely from these. 
LINN. JOURN.— BOTANY, VOL. XLII. 2q 
