OF THE DIFFERENT KINDS OF CENCE, OR MODES OF FLOWERING.
The various modes in which flowers are situated upon or connected with a plant, are of great botanical importance, not only for specific distinctions,but as leading the way to the knowledge of natural fami Fes or orders. Yet Linrimus does not al low them to enter into the generic charac ters of plants, which he founds solely on the seven parts of fructification to be hereafter described This is one of those classical maxims of the Linnman school, which rival botanists are continually at tempting to undermine and depreciate, conscious of their own deficiency in that technical skill for which Linnxus was pre-eminent. We shall take occasion to mention an instance in which he himself went counter to this law.
The following are the several kinds of inflorescence.
1. Verticillus, a whorl, in which the flowers surround the stem in a garland or ring, though perhaps merely inserted on its two opposite sides, as in the natural order to which the mints, the dead nettle, Lamium, and many others, belong. Fig. 25.
2. Racemus, a cluster or raceme, bears several flowers,each in its own ly ranged along one common stalk, like a bunch of currants, and this common stalk may be either simple or branched. A ra cemus is generally drooping or pendulous, and the flowers are all nearly in perfec tion at once. Fig. 26.
3. Spica, a spike, is composed of nu merous crowded flowers, ranged along an upright common stalk, expanding pro gressively and properly, destitute of any partial stalks; but this last circumstance cannot be rigidly observed. Wheat and barley are good examples of a genuine spike. Some lavenders have a compound spike. Spicula, a spikelet, is a term used only for grasses, and expresses that as semblage of florets in a common calyx which constitutes their flowers. Fig. 27.
4. Corymbus, a corymb, fig. 28, may be called a flat-topped spike, the long stalks of whose lowermost flowers raise them to a level with the uppermost, or nearly so; this is exemplified in the cabbage and wall-flower. The yarrow and moun
tain-ash bear a kind of compound and ir regular corymbus, to which is nearly allied, 5. Fasciculus, a fascicle, expressive of a close bundle of flowers, on little stalks, variously connected and level at the top, as in the sweet-william. Fig. 29.
6. Capituturn, a head or tuft, is compos ed of numerous sessile flowers, collected into a globular form, as the globe ama ranthus and thrift. Fig. 30.
7. Umbella, an umbel or rundle, consists of several stalks, called rays, spreading from one common centre, like an umbrel la. Each stalk is either simple and single flowered, or, as most commonly occurs, subdivided into an umbellula, or partial umbel. This inflorescence belongs to natural order, thence called Umbellate, to which the parsley, carrot, hemlock, and many others belong. Fig. 31.
8. Cyma, a cyme, consists of stalks springing from one common centre, but which are afterwards irregularly subdi vided, as in the laurustinus and alder, fig. 32. Linnx.us was led by some con siderations to reckon these two last forms of inflorescence as aggregate flow ers, but it isfound more correct to esteem them modes of inflorescence, though by so doing we lose the advantage of taking parts properly belonging to the umbel into the generic character. By a contrary mode of proceeding we presume to think Linnzetis swerved from his own rule of founding his genera on the actual parts of fructification.
9. Panicula, a panicle, Plate III. fig. 33. is a loose subdivided bunch of flowers, arranged without order, as in the oat. It is either close or spreading. When its branches lean all towards one side, it is called Panicula secunda.
10. Thyrsus, a bunch, is a very dense panicle, inclining to an ovate figure, of which Linnxus cites the lilac and the butter-bur as instances. Dr. Smith adds to these a bunch of grapes, which appears to him to have been inaccurately reckon ed a racemes. Fig. 34.