28 FLOWERS 
elongated stem bearing normally developed leaves in the axils 
of which the flowers occur. Thus, if a Pumpkin or Gourd vine 
should remain short, the flowers instead of being well separated 
as they normally are, would be crowded, and, with the reduction 
of leaves to bracts, a typical flower cluster would result. Most 
small flowers are produced in clusters. For small flowers polli- 
nated by insects, there is considerable advantage in the cluster 
habit, since the cluster, being much 
more conspicuous than the individual 
flowers, serves well as an attractive 
device. 
Flower clusters are divided into 
two main classes according to their 
method of development. In the 
corymbose or indeterminate cluster, 
growth at the tip and the develop- 
ment of new flowers just behind 
continues throughout a considerable 
period, thus producing a cluster in 
which the older flowers are left 
farther and farther behind. As the 
term indeterminate suggests, such a 
method of development permits a 
rather indefinite expansion of the 
cluster. In the cymose or determi- 
nate cluster, the oldest flower is 
formed at the tip, which is thereby 
closed to further growth, and the 
new flowers are formed from buds 
developing lower down. Such a 
cluster is much limited in its power 
to expand. The flower clusters of Apples and Pears, known as 
cymes, illustrate the determinate type of cluster. 
The simplest form of the indeterminate cluster is the raceme, 
an unbranched cluster in which the flowers are borne on short 
stalks. The racemes of the Shepherd’s-purse, Radish, Cabbage, 
and others of the Mustard family, in which the flower cluster 
may continue its expansion for a long period, producing new 
flowers at the tip while pods are maturing at the base, well 
illustrate the nature of the raceme. (Fig. 29.) The racemes of 
Fic. 29.— Raceme of Com- 
mon Cabbage (Brassica). From 
Warming. 
