The duration of inflorescence varies much in different species. In the Peach, Almond, and Apricot, among trees, and in the Hyacinth and Tulip among herbs, it remains in blossom for a few days only. But the Winter Hellebore remains covered with flowers the whole winter, and the Shepherd’s Purse (Capsella) flowers from April till November.

The period at which flowering commences varies in the —_ way according to species. Linnzeus arranged a table of the flowering of different vegetables in the climate of Upsal, in Sweden, for the year 1755, and gave to this list the name of the Floral Calendar.

But this calendar necessarily varies with each climate, for the date of the flowering of a plant is sooner or later, according to the latitude of the country. At Smyrna the Almond-tree blooms in the first half of February; in central France it blooms at the beginning of April; in Germany in the second half of April; at Christiana in the early days of June.

It is hardly necessary to observe here how very indispensable an exact acquaintance with the times of flowering is to those who wish to see flowers succeeding each other harmoniously and without intermission, in their gardens.

INFLORESCENCE.

The arrangement of the flowers on the vegetable is called its inflorescence, from infloresco, “I begin to blossom.” It means simply the flower-head. Schleiden, who has paid more attention to this subject than has been usual with botanists, describes the various forms of inflorescence as follows:—;

I.—Centripetal Inflorescence. 1. The Capitulum, which is many-flowered in CaLatHiuM, whose simple flowers stand on the axils of more or fewer stunted bracts, surrounded with other circles of stunted bracts, as in some of the Composites. 2. The Sprke (Spica) occurs in various fornis, as the Catkin (Amentum), which falls off entire, also distinguished by its imperfect flowers, as in the male flowers of the Betulace@, and some other plants. The Spadix, a closely-crowded -spike, with partially-cylindrical capitulum, and fleshy peduncle. The Cone, a cylindrical capitulum, or solid spike, on which the foliar organs become woody scales. The Spikelet (Spicula), the simple inflorescence of the srasses and Cyperacee: namely, a few-flowered spike, surrounded at the base by Glume, but with flowers having no bracts. 3. The Umset, or Umbellula when compound. 4. The Raceme, which, in different forms, is distinguished as the Corymbe, a pyramidal raceme.:?

TI.— Centrifugal Inflorescence. 5. The Cyne, or false umbel, is a corymbe with centrifugal inflorescence, but includes the compound raceme, umbel, and capitulum. III.— Once Compound Inflorescence. 6. SprkELETs: where several spikes unite in a spiral arrangement, as in the grasses, they become spikelets. 7. Umpetia: where several umbels are united in umbels they become Umbella. 8. The Panicie includes all the many-headed forms of inflorescence, as in many grasses. 9. The Buncu, or Fascicunus: a manifold compound cyme, with short and rather crowded pedicels. 10. The AnrHELA: the inflorescence in the Juncacee (Rushes) and Cyperacee (Reeds). 11. GLomeRuLe: certain forms of inflorescence, resembling Capitulim, consisting of ill-formed, imperfect flowers, as in some nettles and rushes. Flowers are said to be sessile, in the language of botanists, when they are placed immediately on the stalk, or attached immediately to the stalk by a small support, called a peduncle. The peduncle is what is commonly called the stalk of the flower, and afterward becomes the stalk of the fruit. The peduncle therefore is to flowers what the petiole is to leaves, that is, a means of attachment to the stem or branch.

Nevertheless, the analogy between the peduncle and the petiole is limited to the external shape, for the two organs differ essentially in their special organisation.

Do the flowers, whose constituent parts we shall soon consider in detail, spring at random from the stem, the branches, or the boughs supporting them?

Fig. 141.—Inflorescence of the Red Currant (Ribes).

When we consider the admirable regularity and the rigorous laws by which leaves are arranged on the boughs, we are led @ priori to confess that the distribution of flowers on their vegetable axes must obey very determinate laws also. This is, in fact, what is

Fig. 142.—Inflorescence in the sheath of Fig. ig. 143.—Branchi143.—Branching raceme of thethe Oat Oat. Vervein Omcbatn

shown us by nature. Her laws are generally easily recognised and though sometimes hidden, are never violated. Flowers are always the termination of an axis, branch, or bough, and the order governing their arrangement is only a repetition of that which regulates the ramification of the plant.

Fig. 142.—Inflorescence Vervein Omcbatn in the sheath of

Fig. 147. —Simple umbel of Astrantia.

Figs. 148 and 149.—Inflorescence of the Daisy.

. 129 THE FLOWER.

In order to study inflorescence generally, let us take some of the \ more common plants and examine the arrangement of the flowers on each of them. In the Red Currant (Fig. 141), the floral axis carries at intervals modified leaves, called bracts; at the axil of each of these bracts the peduncle takes its rise, and it is terminated by a flower. This is the type of the cluster (or raceme). The inflorescence of the Vervain (Verbena officinalis), Fig. 142, is only distinguished from the above by the extreme shortness of the peduncles; this constitutes a spike. The Oat-plant (Fig. 143) furnishes us with an example of the modifications which the cluster experiences. Its flower is called a branching cluster, or raceme. The spike takes the name of catkin or ament, from amentum, a strap, when it is formed of unisexual flowers, as represented in the male and female catkins of the Willow, Figs. 144 and 145.

In the Cherry of St. Lucia (Fig. 146), the peduncles originating in the principal axis are longer ‘at the lower part of the axis than they are towards the summit, so that the whole of the flowers form together a sort of umbel with unequal ribs; this cluster is called a corymbe. In the Astrantia (Fig. 147), so called from its star-like flowers, the axis of inflorescence is very short, and bears at the extremity, which is enlarged, a certaif number of secondary axils, rather elongated, and of equal length, so that the flowers seem to spring from the same point in order to attain the same height. Here the umbel has equal ribs, and the group of flowers is said to be umbelliferous. In the Daisy (Figs. 148, 149) the numerous sessile flowers are inserted on the surface of an enlarged and flattened axis, and form - a capitulum, or head. The capitulum is influenced by the form of the receptacle: when the latter is spherical, the capitulum is globular; when flat, concave, or convex, the capitulum varies nocordlingly. i All these modes of inflorescence are only modifications of one of them, which may be taken as a type, namely, the cluster. They Sometimes seem to attain a certain degree of complication, without having the simplicity of their guiding rule thereby diminished.

Thus, in the Nettle-tree (Fig. 150) the clusters of flowers are K

Fig. 151.—Compound umbel of the Chervil. Fig. 152.—Compound raceme of the Vine.

arranged in a corymb. In the Carrot and Chervil, Fig..151, the umbels rising from the summit of the stem, each pedicel has an umbel on its summit, when they become a compound umbel. In the Privet, and the Vine, Fig. 152, the inflorescence is formed of small clusters, being again arranged in larger clusters, or panicles.

Fig. 153.—Compound spike of Wheat. Fig. 154.—Dich@tomous cyme of Centaury. In the Wheat-plant, Fig. 153, the ears: are grouped in spikes. There are, then, compound corymbs, compound umbels, compound clusters, or panicles, and compound spikes. In every case hitherto mentioned, the number of flowers of the Same generation are indeterminate in each group. This will not be the case in the following instances. oe

Let us examine, for example, the method of arrangement in the flowers of the Centaury (Erythrea Centaurium), Fig. 154. The main stem terminates with a flower, and a little below this the stem bears two opposite leaves or bracts. From the axil of each of these arises a secondary branch, terminated also in two leaves and a flower. ach of these branches comport themselves in the same way as the stem, that is, they give birth to two tertiary branches,

i Ma

Fig. 155.—Inflorescence of Myosotis. Fig. 156.—Spathe of Arum maculatum. each terminating in a flower, and thus it goes on. We thus see that at each branching out, the number of flowers is doubled. We see besides, that the flowering in this plant goes from the base to the summit, or, which comes to the same thing, from the centre to the circumference. This sort of inflorescence bears the name of a cyme, and in this particular case is said to be dichotomous,

from diya and reuvw, “by pairs I divide.” In some cases three whorled bracts develop axes from their axils, when the cyme is said to be trichotomous, divided by threes. e inflorescence of the Forget-me-not (Myosoti), and the Heliotrope, also form cymes. As in these plants the multiplying axis of inflorescence often tends to form a curling inflorescence, very unfitly compared to the tail of a scorpion, the cyme of the Forget-me-not and Heliotrope are said in consequence to be scorpiodal (Fig. 155). In the Horse Chesnut, the principal axis bears an indeterminate number of small scorpioidal cymes. This is an inflorescence mixed up of the two principal forms we have already pointed out, and is a cluster of scorpioidal cymes. When a succulent spike is enclosed within a spathe, it is said to be spadix, from oradié, a palm branch with its fruit. In this case the axis is usually elongated beyond the flowers in the form of a club-shaped cellular organ, as in the Cuckoo-pint (Arum maculatum), Fig. 156, or the axis only bears flowers at its base, which is here enclosed by the spathe.

The general name of involucre is given to a more or less considerable collection of bracts, disposed in whorls (verticils) in either one or several ranks, which surround and seem to protect the flowers (the capitulum of composite flowers), yet in the natural group of Arums, the involucre is monophyllous, and is called a Spathe. It envelopes the inflorescence before the blowing of the flowers. We show in Fig. 156 the spathe of the Arum maculatum. We should exhaust the attention of the reader were we to enlarge more on inflorescence, a subject which we have only glanced at, but which has been the object of profound study on the part of botanists. We now come to the consideration of the constituting parts of the flower.

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