80 OBJECT LESSONS IN BOTANY. 
itself an umbel. These secondary 
umbels we call wmbellets. At the 
base of the umbel there is usually a 
whorl of bracts forming an involucre 
(a), and often also at the base of 
each umbellet (6), when we call it an 
involucel. 
153. The fine flowers of the Ca- 
talpa are in panicles (Fig. 235), also 
the flowers of Oats. Wemay describe 
a panicle as if a raceme should have 
its pedicels irregularly branched. 
154. A cluster resembling a pani- 
cle, but more compact, such as you 
see in Lilac, is called a thyrse. 
155. A head of flowers, such as we Behe Mee an ee an 
see in Clover or the Button-bush, 
hardly needs description. We might say that the head is a 
reduced umbel, having its flowers all sessile at the top of the 
peduncle. _ 
156. The great family of the Asterworts has all its flowers 
in heads, so dense and so nicely arranged as to be easily mis- 
taken for a single flower. But if you carefully examine such 
a head, say of an Aster, or especially of a Sunflower, you 
will see that it is composed of many little flowers or florets. 
The florets of the outer row are enlarged and open, so as to 
does that of Carrot differ? What is an umbellet? What the whorl of 
practs at the base of the umbellets? 
158. Please describe the panicle. 154. The thyrse. 155. The head. 
156. What the inflorescence of the Asterworts? How is the head of Aster 
made to resemble a single flower? What the florets of theray? What the 
florets of the disk ? 
