STRUCTURE.] CUPULE PALEiE SPATHE. 311 



call these exterior bracts bractlets, and to say that an involucre 

 in which they are present is basi bracteolatum, bracteolate at 

 the base. 



Another form of the involucre is the cupule (fig. 66.) It 

 consists of bracts not much developed till after flowering, 

 when they cohere by their bases, and form a kind of cup. 

 In the Oak the cupule is woody, entire, and scaly, with indu- 

 rated bracts : in the Beech it forms a sort of coriaceous, 

 valvular, spurious pericarp : in the Hazel Nut (fig. 65.) it is 

 foliaceous and lacerated.* 



In Euphorbia the involucre is composed of two whorls of 

 bracts, consolidated into a cup, and assumes altogether the 

 appearance of a calyx, for which it was for a long time 

 mistaken. 



The name squama or scales is usually applied to the bracts 

 of the catkin; it is also occasionally used to indicate any kind 

 of bract which has a scaly appearance. 



The bracts which are stationed upon the receptacle of 

 Composites, between the florets, have generally a membranous 

 texture and no colour, and are called palea, Englished by some 

 botanists chaff of the receptacle. The French call this sort of 

 bract paillette, Cassini squamelles. 



In Palms and Arads there is seated at the base of the 

 spadix, a large coloured bract, in which the spadix, during 

 aestivation, is wholly enwrapped, and which may, perhaps, 

 perform in those plants the office of corolla. This is called 

 the spat he (fig. 83.) Link considers it a modification of the 

 petiole. (Elementa, p. 253.) 



The most remarkable arrangement of bracts takes place in 

 Grasses, in which they occupy the place of calyx and corolla, 

 and have received a variety of names from different systematic 

 writers. In order to explain the application of these terms, 

 it is necessary to describe with some minuteness the struc- 

 ture of a locusta or spikelet, as the partial inflorescence of 

 Grasses is denominated. Take, for example, any common 

 Bromus ; each spikelet will be seen to have at its base two 

 opposite empty bracts (fig. 67. b), one of which is attached to 



* What has been called the cupule of the Yew is said by Schleiden to be a 

 late development of the primine of the ovule. 



