Fig. 217. Diagram of analogous scorpioid cyme, with alternate leaves or bracts.
226. These distinctions between determinate and indeterminate inflorescence, between corymbs and cymes, and between the true and the false raceme and spike, were not recognized by botanists much more than half a century ago, and even now are not always attended to in descriptions. It is still usual and convenient to describe rounded or flat-topped and open ramification as corymbose, even when essentially cymose; also to call the reversed or false racemes or spikes by these (strictly incorrect) names.
[227.] Mixed Inflorescence is that in which the two plans are mixed or combined in compound clusters. A mixed panicle is one in which, while the primary ramification is of the indeterminate order, the secondary or ultimate is wholly or partly of the determinate order. A contracted or elongated inflorescence of this sort is called a Thyrsus. Lilac and Horse-chestnut afford common examples of mixed inflorescence of this sort. When loose and open such flower-clusters are called by the general name of Panicles. The heads of Compositæ are centripetal; but the branches or peduncles which bear the heads are usually of centrifugal order.
[§ 2.] PARTS OR ORGANS OF THE FLOWER.
228. These were simply indicated in Section II. [16]. Some parts are necessary to seed-bearing; these are Essential Organs, namely, the Stamens and Pistils. Others serve for protection or for attraction, often for both. Such are the leaves of the Flower, or the Floral Envelopes.
[229.] The Floral Envelopes, taken together, are sometimes called the Perianth, also Perigone, in Latin form Perigonium. In a flower which possesses its full number of organs, the floral envelopes are of two kinds, namely, an outer circle, the Calyx, and an inner, the Corolla.
[230.] The Calyx is commonly a circle of green or greenish leaves, but not always. It may be the most brightly colored part of the blossom. Each calyx-leaf or piece is called a Sepal.
[231.] The Corolla is the inner circle of floral envelopes or flower-leaves, usually of delicate texture and colored, that is, of some other color than green. Each corolla-leaf is called a Petal.
232. There are flowers in abundance which consist wholly of floral envelopes. Such are the so-called full double flowers, of which the choicer roses and camellias of the cultivator are familiar examples. In them, under the gardener's care and selection, petals have taken the place of both stamens and pistils. These are monstrous or unnatural flowers, incapable of producing seed, and subservient only to human gratification. Their common name of double flowers is not a sensible one: except that it is fixed by custom, it were better to translate their Latin name, flores pleni, and call them full flowers, meaning full of leaves.