MANUAL/ OF NATURE STUDY. 
153 
take the form of a raceme ? Of a corymb ? Of an 
umbel ? 
Shorten the axis of the plantain until the sessile 
flowers arise from about the same point and the 
flower cluster would be called a Head . The button- 
wood or sycamore ball is a head. How is a head 
different from an umbel? A spike different from 
a raceme ? The spadix , as in Indian turnip, the 
catkin , as in birch, willow or alder are simply dif¬ 
ferent modifications of the spike . 
Broaden the receptacle of the head and surround 
it with a set of bracts called involucre and you have 
a composite flower. Examine the dandelion, iron 
weed, ox-eyed daisy, dog fennel and sun flower. 
In what respect are these flowers different from a 
clover blossom, or button-wood ball? 
The teacher may be able to trace the determinate 
inflorescence to the compositae in the same way as 
with the indeterminate. 
The cyme of the determinate corresponds with 
the raceme of the indeterminate. In the determin¬ 
ate inflorescence the flowering is centrifugal, that 
is, the oldest flower is in the center and the order 
of flowering is outward. In the indeterminate 
iuflorescence the mode of flowering is centripetal, 
that is, beginning on the outside and flowering 
toward the center. 
