BRACTS AND FLORAL LEAVES. 79 
above described. ‘Thus there are compound racemes and corymbs, 
where the branches of highest order are themselves racemes and 
corymbs. If the branching is irregular, a panicle is the result. 
The large group of Umbelliferze is characterized by the occur- 
rence of umbels, usually compound. Hence the name. Carrot, 
parsnip, hemlock, and the like are examples. Bracts may be 
absent or form a general involucre round the origins of the 
primary branches, and partial ones where the branch or par- 
tial umbels arise. Compound spikes occur in many grasses, 
It does not always happen that the branching is of the same 
kind throughout. Thus, in grasses, the spikelets (¢.e., small 
spikes) are not always arranged in compound spikes, but may be 
in racemes or panicles, 
Cymose or definite inflorescences branch in the way already 
described on p. 24. They are called “definite” because the main 
axis after producing a flower at its end ceases to elongate, and 
is overtopped by its branches, which grow in the same manner. 
Simple and compound cymes may be distinguished. Taking the 
former first, a subdivision may be made into forms where a 
pseudaxis or sympodium is (1) absent, (2) present. The false 
dichotomy of mistletoe (p. 4) exemplifies the first kind, and so 
do the dichotomous or two-rayed cymes of cainpion and stitchwort 
(cf. fig. 35), where, however, the end of the main axis is of fair 
FIG. 35.—Forked Cyme. Fig. 36.—Helicoid Cyme of 
Forget-me-not. 
length, and bears a flower, so that the forking is obviously due 
to lateral branches. The central flower opens first, then those 
terminating the first pair of branches, and so on. For this 
reason cymose inflorescences have been called centrifugal. A 
