SECTION 8.] 



INFLORESCENCE. 



75 



whicli arc sessile on a very short axis or receptacle, as in the Button-ball, 

 Button-busli (Fig. '205), and Red Clover. It is just what a spike -would 



205 20G 



toecome if its axis were shortened ; or an umbel, if its pedicels were all 

 shortened until the flowers became sessile. The head 

 of the Button-bush is naked ; but that of tlie Thistle, 

 of the Dandelion, and the like, is surrounded by empty 

 bracts, which form an Inmlucre. Two particular forms 

 of the spike and the head have received particular 

 names, namely, the Spadix and the Catkin. 



212. A Spadix is a fleshy spike or head, with small 

 and often imperfect flowers, as in the Calla, Indian 

 Turnip, (Fig. 206), Sweet Flag, etc. It is commonly 

 surrounded or embraced by a peculiar enveloping leaf, 

 called a Sp.\tiie. 



213. A Catkin, or Ament, is the name given to the 

 scaly sort of si)ike of the Birch (Fig. 20?) and Alder, 

 the Willow and Poplar, and one sort of flower-clusters 

 of the Oak, Hickory, and the like, — the so-called Jmeii- 

 taceom trees. 



214. Compound flower-clusters of these kinds are 

 not uncommon. When the stalks which in the sim- 

 ple umbel are the pedicels of single flowers themselves 

 branch into an umbel, a Compound Umbel is formed. 207 



Fig. 205. Head of the Buttoii-lnish (Cepbalanthus). 



Fig. 206. Sjiadix ainl si)atlic of tlie Indian Turnip;, the latter cut through belo* 



Fig. 207. Calkin, or Ament, of Bircli. 



