215. The secondary or partial umbels of a compound umbel are UMBELLETS. When the umbellets are subtended by an involucre, this secondary involucre is called an INVOLUCEL. 216. A _Compound raceme_ is a cluster of racemes racemosely arranged, as in Smilacina racemosa. A _compound corymb_ is a corymb some branches of which branch again in the same way, as in Mountain Ash. A _compound spike_ is a spicately disposed cluster of spikes. [Illustration: Fig. 209. Diagram of a simple panicle.] 217. =A Panicle=, such as that of Oats and many Grasses, is a compound flower-cluster of a more or less open sort which branches with apparent irregularity, neither into corymbs nor racemes. Fig. 209 represents the simplest panicle. It is, as it were, a raceme of which some of the pedicels have branched so as to bear a few flowers on pedicels of their own, while others remain simple. A _compound panicle_ is one that branches in this way again and again. [Illustration: Fig. 210. Diagram of an opposite-leaved plant, with a single terminal flower. 211. Same, with a cyme of three flowers; _a_, the first flower, of the main axis; _b b_, those of branches. 212. Same, with flowers also of the third order, _c c_.] 218. =Determinate Inflorescence= is that in which the flowers are from terminal buds. The simplest case is that of a solitary terminal flower, as in Fig. 210. This stops the growth of the stem; for its terminal bud, becoming a blossom, can no more lengthen in the manner of a leaf-bud. Any further growth must be from axillary buds developing into branches. If such branches are leafy shoots, at length terminated by single blossoms, the inflorescence still consists of solitary flowers at the summit of stem and branches. But if the flowering branches bear only bracts in place of ordinary leaves, the result is the kind of flower-cluster called 219. =A Cyme.= This is commonly a flat-topped or convex flower-cluster, like a corymb, only the blossoms are from terminal buds. Fig. 211 illustrates the simplest cyme in a plant with opposite leaves, namely, with three flowers. The middle flower, _a_, terminates the stem; the two others, _b b_, terminate branches, one from the axil of each of the uppermost leaves; and being later than the middle one, the flowering proceeds from the centre outwards, or is _Centrifugal_. This is the opposite of the indeterminate mode, or that where all the flower-buds are axillary. If flowering branches appear from the axils below, the lower ones are the later, so that the order of blossoming continues _centrifugal_ or, which is the same thing, _descending_, as in Fig. 213, making a sort of reversed raceme or _false raceme_,--a kind of cluster which is to the true raceme just what the flat cyme is to the corymb. [Illustration: Fig. 213. Diagram of a simple cyme in which the axis lengthens, so as to take the form of a raceme.]