When an indeterminate flower-cluster is short, so that the _top is convex or flat_, it is a =corymb= (Fig. 217). The outermost flowers open first. Centripetal flower-clusters are sometimes said to be corymbose in mode. When the branches of an indeterminate cluster _arise from a common point_, like the frame of an umbrella, the cluster is an =umbel= (Fig. 218). Typical umbels occur in carrot, parsnip, caraway and other plants of the parsley family: the family is known as the Umbelliferæ, or umbel-bearing family. In the carrot and many other Umbelliferæ, there are small or secondary umbels, called =umbellets=, at the end of each of the main branches. (In the center of the wild carrot umbel one often finds a single, blackish, often aborted flower, comprising a 1-flowered umbellet.) [Illustration: FIG. 218.--REMAINS OF A LAST YEAR’S UMBEL OF WILD CARROT.] =Centrifugal or Determinate Clusters.=--When the terminal or central flower opens first, the cluster is said to be =centrifugal=. The growth of the shoot or cluster is =determinate=, since the length is definitely determined or stopped by the terminal flower. Fig. 219 shows a determinate or centrifugal mode of flower bearing. Dense centrifugal clusters are usually flattish on top because of the cessation of growth in the main or central axis. These compact flower-clusters are known as =cymes=. Centrifugal clusters are sometimes said to be cymose in mode. Apples, pears (Fig. 220), and elders bear flowers in cymes. Some cyme-forms are like umbels in general appearance. A head-like cymose cluster is a =glomerule=; it blooms from the top downwards rather than from the base upwards. =Mixed Clusters.=--Often the cluster is mixed, being determinate in one part and indeterminate in another part of the same cluster. The main cluster may be indeterminate, but the branches determinate. The cluster has the appearance of a panicle, and is usually so called, but it is really a =thyrse=. Lilac is a familiar example of a thyrse. In some cases the main cluster is determinate and the branches are indeterminate, as in hydrangea and elder. [Illustration: FIG. 219.--DETERMINATE OR CYMOSE ARRANGEMENT.--Wild geranium.] [Illustration: FIG. 220.--CYME OF PEAR. Often imperfect.] =Inflorescence.=--The mode or method of flower arrangement is known as the =inflorescence=. That is, the inflorescence is cymose, corymbose, paniculate, spicate, solitary, determinate, indeterminate. By custom, however, the word “inflorescence” has come to be used for the _flower-cluster itself_ in works on descriptive botany. Thus a cyme or a panicle may be called an inflorescence. It will be seen that even solitary flowers follow either indeterminate or determinate methods of branching. [Illustration: FIG. 221.--FORMS OF CENTRIPETAL FLOWER-CLUSTERS. 1, raceme; 2, spike; 3, umbel; 4, head or anthodium; 5, corymb.] [Illustration: FIG. 222.--CENTRIPETAL INFLORESCENCE, _continued_. 6, spadix; 7, compound umbel; 8, catkin.]