24 



CAPITULUM : SPIKE 



[CH. 



are also usually crowded round the insertion of the pedicels, 

 or the base and margin of the receptacle, and form an 

 Involucre. Examples of capitula are common in herba- 

 ceous plants, but very rare in shrubs or trees : they are 



B 



Fig. 7. Capitulum. A, with a conoid receptacle, on which the florets 

 are sessile, each in the axil of its bract, in acropetal order ; if the recep- 

 tacle were somewhat more elongated this capitulum would pass into the 

 spike. B, with an expanded and slightly depressed receptacle, the florets 

 in centripetal order; if somewhat more depressed in the centre, and the 

 margins approximated above, the florets would line a hollow receptacle, 

 as actually occurs in the Fig. 



characteristic of Compositse, Sunflower, Daisy, Thistle, 

 &c., and their relation to the umbel and to the following 

 inflorescence (Spike) may be traced in the Teazle, Acacia, 

 Clovers, &c. The extremely dilated inflorescence of Do7-- 

 stenia is essentially of the same nature, as is also the 

 large clavate one of Artocarpus, and the hollowed or 

 introverted form of the Fig, all of which inflorescences are 



