correlated with the length of proboscis of the visiting insect. When the flower opens, the two stigmas are pressed together below the tube formed by the anthers, the latter split on the inside, and the pollen fills the tube; the style gradually lengthens and carries the pollen out of the anther tube, and finally the stigmas spread and expose their receptive surface which has hitherto been hidden, the two being pressed together. Thus the life history of the flower falls into two stages, an earlier or male and a later or female. This favours cross-pollination as compared with self-pollination. In many cases there is a third stage, as in dandelion, where the stigmas finally curl back so that they touch any pollen grains which have been left on the style, thus ensuring self-pollination if cross-pollination has not been effected.
The devices for distribution of the fruit are very varied. Frequently there is a hairy or silky pappus forming a tuft of hairs, as in thistle or coltsfoot, or a parachute-like structure as in dandelion; these render the fruit sufficiently light to be carried by the wind. In Bidens the pappus consists of two or more stiff-barbed bristles which cause the fruit to cling to the coats of animals. Occasionally, as in sunflower or daisy, the fruits bear no special appendage and remain on the head until jerked off.
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| Fig. 2.—Flowering shoot of Cornflower. 1. Disk-floret in vertical section. |
Compositae are generally considered to represent the most highly developed order of flowering plants. By the massing of the flowers in heads great economy is effected in the material required for one flower, as conspicuousness is ensured by the association; economy of time on the part of the pollinating insect is also effected, as a large number of flowers are visited at one time. The floral mechanism is both simple and effective, favouring cross-pollination, but ensuring self-pollination should that fail. The means of seed-distribution are also very effective.
A few members of the order are of economic value, e.g. Lactuca (lettuce; q.v.), Cichorium (chicory; q.v.), Cynara (artichoke and cardoon; q.v.), Helianthus (Jerusalem artichoke). Many are cultivated as garden or greenhouse plants, such as Solidago (golden rod), Ageratum, Aster (q.v.) (Michaelmas daisy), Helichrysum (everlasting), Zinnia, Rudbeckia, Helianthus (sunflower), Coreopsis, Dahlia (q.v.), Tagetes (French and African marigold), Gaillardia, Achillea (yarrow), Chrysanthemum, Pyrethrum (feverfew; now generally included under Chrysanthemum), Tanacetum (tansy), Arnica, Doronicum, Cineraria Calendula (common marigold) (fig. 1), Echinops (globe thistle), Centaurea (cornflower) (fig. 2). Some are of medicinal value, such as Anthemis (chamomile), Artemisia (wormwood), Tussilago (coltsfoot), Arnica. Insect powder is prepared from species of Pyrethrum.
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| Fig. 3.—Groundsel (Senecio vulgaris). | |
| 1. Disk-floret. | 3. Ray-floret. |
| 2. Same cut vertically. | 4. Fruit with pappus. |
The order is divided into two suborders:—Tubuliflorae, characterized by absence of latex, and the florets of the disk being not ligulate, and Liguliflorae, characterized by presence of latex and all the florets being ligulate. The first suborder contains the majority of the genera, and is divided into a number of tribes, characterized by the form of the anthers and styles, the presence or absence of scales on the receptacle, and the similarity or otherwise of the florets of one and the same head. The order is well represented in Britain, in which forty-two genera are native. These include some of the commonest weeds, such as dandelion (Taraxacum Dens-leonis), daisy (Bellis perennis), groundsel (fig. 3) (Senecio vulgaris) and ragwort (S. Jacobaea); coltsfoot (Tussilago Farfara) is one of the earliest plants to flower, and other genera are Chrysanthemum (ox-eye daisy and corn-marigold), Arctium (burdock), Centaurea (knapweed and cornflower), Carduus and Cnicus (thistles), Hieracium (hawkweed), Sonchus (sow-thistle), Achillea (yarrow, or milfoil, and sneezewort), Eupatorium (hemp-agrimony), Gnaphalium (cudweed), Erigeron (fleabane), Solidago (golden-rod), Anthemis (may-weed and chamomile), Cichorium (chicory), Lapsana (nipplewort), Crepis (hawk’s-beard), Hypochaeris (cat’s-ear), and Tragopogon (goat’s-beard).
COMPOSITE ORDER, in architecture, a compound of the
Ionic and Corinthian orders (see Order), the chief characteristic
of which is found in the capital (q.v.), where a double row of
acanthus leaves, similar to those carved round the Corinthian
capital, has been added under the Ionic volutes. The richer
decoration of the Ionic capital had already been employed in
those of the Erechtheum, where the necking was carved with
the palmette or honeysuckle. Similar decorated Ionic capitals
were found in the forum of Trajan. The earliest example of the
Composite capital is found in the arch of Titus at Rome. The
entablature was borrowed from that of the Corinthian order.
COMPOSITION (Lat. compositio, from componere, to put together), the action of putting together and combining, and the
product of such action. There are many applications of the
word. In philology it is used of the putting together of two
distinct words to form a single word; and in grammar, of the
combination of words into sentences, and sentences into periods,
and then applied to the result of such combination, and to the
art of producing a work in prose or verse, or to the work itself.
In music “composition” is used both of the art of combining
musical sounds in accordance with the rules of musical form,
and, more generally, of the whole art of creation or invention.
The name “composer” is thus particularly applied to the
musical creator in general. In the other fine arts the word is
