2 ba ELEMENTS OF BOTANY. 
The Raceme and Related Forms. —If the leaves along the 
stem were to become very much dwarfed and the flowers 
brought closer together, as they frequently are, a kind of 
flower-cluster like that of the currant (Fig. 105) or the lily of 
the valley would result. Such an inflorescence is called a 
raceme ; the main flower stalk is known as the peduncle ; the 
little individual flower stalks are pedicels, and the small, more 
or less scale-like leaves of the peduncle are bracts.’ 
Frequently the lower pedicels of a cluster on the general 
plan of the raceme are longer than the upper ones and make 
a somewhat flat-topped cluster, like 
that of. the hawthorn, the sheep 
laurel, or the trumpet creeper. 
This is called a corymb. 
In many cases, for example the 
parsnip, the sweet cicely, the gin- 
seng and the cherry, a group of 
pedicels of nearly equal length 
spring from about the same point. 
This produces a flower-cluster called 
the umbel (Fig. 106). 
-166. Sessile Flowers and Flower- 
Clusters. —Often the pedicels are 
F1G.106.—Simple Umbelof Cherry. Wanting, or the flowers are sessile, 
and then a modification of the 
raceme is produced which is called a spike, like that of the 
plantain (Fig. 107). The willow, alder, birch, poplar, and 
many other common trees bear a short, flexible, rather scaly 
spike (Fig. 108), which is called a catkin. 
The peduncle of a spike is often so much shortened as to 
bring the flowers into a somewhat globular mass. This is 
' 1It is hardly necessary to say that the teacher will find it better in every way, if 
material is abundant, to begin the study of flower-clusters with the examination of 
typical specimens by the class. 
