CHAP. II. 
BRACTS. 
147 
of the stem. In fact, there is in many cases no other mode 
than ascertaining the usual number of sepals in other plants 
of the same natural order, and considering every leaf-like 
appendage on the outside of the usual number of sepals as a 
bract. In Camellia, for example, if it were not known that 
the normal number of sepals of kindred genera is five, it 
would be impossible to determine the number of its sepals. 
When the bracts are very small, they are called bractlets ; or, 
if they are of difterent sizes upon the same inflorescence, 
the smallest receive that name. It rarely occurs that an 
inflorescence is destitute of bracts. In Cruciferac this is a 
general character, and is observed by Link to indicate an 
extremely irregular structure. When bracts do not imme- 
diately support a flower or its stalk, they are called empty 
(vacuce). As a general rule, it is to be understood, that what- 
ever intervenes between the true leaves and the calyx, whatever 
be their form, colour, size, or other peculiarity, comes within 
the meaning of the term. 
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 Apiaceous 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 Composite, the involucre often consists 
of several rows of imbricated bracts, and has received a 
variety of names, for none of which there appears to be 
occasion. Linnaeus called it calyx communis, Necker perigy-^ 
nandra communis, Richard periphorantliium, Cassini peri^ 
clinium. There is often found at the base of the involucre 
of Compositae an exterior rank of bracts, which Linnaeus 
called calyculus ; and such involucres as w^ere so circumstanced 
calyx calyculatus. Cassini restricts the term involucre to this ; 
but it seems most convenient to call these exterior bracts 
bractlets, and to say that an involucre in which they are pre- 
sent is basi bracteolatum, bracteolate at the base. 
L 2 
