80 



OBJECT LESSONS IN BOTANY. 



itself an umbel. These secondary 

 umbels we call icmhellets. At the 

 base of the umbel there is usually a 

 whorl of bracts forming an involucre 

 («), and often also at the base of 

 each umbellet (Z>), when we call it an 

 hivohicel. 



153. The fine flowers of tlie Ca- 

 talpa are in jpanicles (Fig. 235), also 

 the flowers of Oats. We may 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 j^ou 

 see in Lilac, is called a thyrse. 



155. A head of flowers, such as we 

 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 lias 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 



Fig. 244. Compound umbel 

 of Sweet Cicely {Osmorhlza). 



does that of Carrot differ? What is an umbellet? What the whorl of 

 bracts at the base of the umbellets ? 



153. 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 the ray ? What the 

 florets of the disk ? 



