124 
ORGANOGRAPHY. 
BOOK I. 
Under particular circumstances bracts have received the 
following peculiar names : — 
When they are empty, and terminate the inflorescence, they 
form a coma^ as in Salvia Horminum. In this case they are 
generally enlarged and coloured. 
If they are verticillate, and surround several flowers, they 
constitute an involucre. In Umbelliferous plants, the bracts 
which surround the general umbel are called an universal 
involucre ; and those which surround the umbellules a partial 
involucre, or involucellum. In Compositse, the involucre 
often consists of several rows of imbricated bracts, and has 
received a variety of names, for none of which does there 
appear to be the least occasion. Linnaeus called it calyx 
communis, Necker perigynandra coynmunis, Richard periplior- 
anthium, Cassini periclinium. There is often found at the 
base of the involucre of Compositse an exterior rank of 
bracts, which Linnaeus called caly cuius ; and such involucres 
as were so circumstanced calyx cahjculatus, Cassini restricts 
the term involucre to this ; but it seems most convenient to 
call these exterior bracts bractlet's, and to say that an involu- 
cre in which they are present is basi bracteolatus, bracteolate 
at the base. 
Another and very remarkable form of the involucre is the 
cupula (Jig. 67.). It consists of bracts not developed till after 
flowering, when they cohere by their bases, and form a kind 
of cup. In the Oak the cupula is woody, entire, and scaly, 
with indurated bracts : in the Beech it forms a sort of 
coriaceous valvular spurious pericarp : in the Hazel Nut 
(Jig. 65.) it is foliaceous and lacerated: in the Yew it is fleshy 
and entire, with no appearance of bract. 
The name squama or scale 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 
Compositae, between the florets, have generally a membranous 
texture and no colour, and are called palece, Englished by 
some botanists chaff of the receptacle. The French call this 
sort o^ hmci paillette, Cassini squamellcs (Jig. 64.). 
In Palms and Aroideae there are seated, at the base of the 
