182 



ORGANOGBAPHY. 



Certain varieties of arrangement and forms of bracts have 

 received special names. Thus the bracts of that kind of inflo- 

 rescence called an Amentum or Catkin {jig. 371) (see page 191), 

 as seen in the Willow, Oak, Birch, &c., are termed squamce or 

 scales, or the bracts are described as squamous or scaly. 



Fig. 372. 



Fig. 371. Staminate or male catkin of the Hazel, showing a number of 



scaly bracts between the flowers. Fig.Z12. Compound umbel of the 



Carrot {Bmicus Carota). a. General involucre, b, b. Partial involucres. 



When a circle or whorl of bracts is placed round one flower, as 

 in the Mallow {fig. 369) and Strawberry {fig. 370); or a number 

 of flowers, as in the Carrot {fig. 372) and most other umbelli- 

 ferous plants, they form what is termed an involucre. In some 

 umbelliferous plants, as for instance the Carrot {fig. 372), there 

 are two kinds of involucre, one at the base of the primary divi- 

 sions of the floral axis or general umbel {a) (see page 196); and 

 another at the base of each of the partial umbels or umbellules 

 {h); the former is then called the general involucre; and each 

 of the latter an involucel or 'partial involucre. In plants of the 

 natural order Compositse, as the Marygold {fig. 373), Artichoke, 

 Chamomile, Daisy, &c., and of some allied orders, a somewhat 

 similar arrangement of bracts takes place, and the name of in- 

 volucre is also applied to them. In these cases there are fre- 

 quently two or three rows of bracts overlapping each other. 

 The constituent bracts thus forming the involucre of Com- 

 posite flowers have been termed phyllaries. Sometimes the 

 bracts of an involucre grow together at their base, and form 

 ultimately a sort of cup-shaped body surrounding the fruit, as 



