80 



OBJEeT LESSONS IN BOTANY. 



itself an umbel. These secondary- 

 umbels we call wnrubellets. 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 ib), when we call it an 

 involucel. 



153. The fine flowers of tlie Ca- 

 talpa are in panicles (Fig. 235), also 

 the flowers of Oats. We may describe 

 a panicle as if a raceme should have 

 its pedicels irregularly branched. 



154. A duster resembling a pani- 

 cle, but more compact, such as you 

 see in Lilac, is oalled a thyrse. 

 ■ 155. A liead 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. 



'1«66. 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 yoi^, 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 floi-ets of the outer row are enlarged and open, so as to 



Fig. 244. Compound iiiiibeUJ?/ 

 of Sweet Cicely (Oarrwrhiza). 



does that of Carrot differ ? What is au 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 1 What the florets of the ray ? What the 

 florets of the disk ? 



