526 



NATURAL HISTORY OF PLANTS. 



depressed. The exterior bracts are foliaceous, united at the base ; ^ 

 the interior are much smaller and may be reduced to simple scales. 

 In B. scapigera, raised to the rank of a genus under the name of 



Nastanthus,^ the peduncles of the 



Calycera eri/)wioides. • n i i 1 1 • i 



* mnorescence are short, thick, 

 leafless and surmounted by a 

 single floral mass. The same is 

 true of B. squarrosa, &c. of which 

 a genus, Acarplia,^ has been 

 formed ; but the peduncle bears 

 some small leaves ; the scales of 

 the involucre are all or for the 

 most part little developed and 

 the angles of the fruit are pro- 

 minent. 



Near Boopis are placed the 

 genera Acicarplia and Cahjcera 

 (fig. 431,432), which really difi'er 

 little from it. In both the glo- 

 merules are formed of flowers of 

 centrifugal evolution, often in- 

 serted in the indentations of the 

 receptacle ; the most external of 

 these flowers are more backward 

 than the others and remain small 

 or even fail to develop their fe- 

 male organs. In Cahjcera {Q.g. 

 431, 432), the calyx lobes or 

 some of them are lengthened 

 into hard spines, particularly in the sterile flowers, and are little or 

 not at all changed in the fertile flowers. In Acicarpha, the interior 

 cymes are formed of sterile flowers the ovaries of which remain 

 completely free ; whilst the fruits which succeed the fertile flowers of 

 the periphery are more or less surrounded by the receptacle accrescent^ 



Fig. 432. Long. sect, of flower (f ). 



^ As especially in Gamocarpha (DC. Prodr. v. 

 2;— Endl. Gen. n. 3033 ,— AIiers, Goutriy.ii. 

 18, t. 45), in which the tube of the corolla is 

 slightly enlarged at the base. 



2 MiERS, Contrib. ii. 12, t. 43, 41. 



3 Griseb. Bein. PL Phil, und Lechl. 37 {Abh. 

 K. Ges. Wiss. Gott. 1854). 



•1 Unequally thickened, according to the 

 locality. 



