A remarkable feature of the distribution of grasses is its uniformity; there are no great centres for the order, as in Compositae, where a marked preponderance of endemic species exists; and the genera, except some of the smallest or monotypic ones, have usually a wide distribution.
Advance has been along two lines, markedly in relation to insect-pollination, one of which has culminated in the hypogynous epipetalous bicarpellate forms with dorsiventral often large and loosely arranged flowers such as occur in Scrophulariaceae, and the other in the epigynous bicarpellate small-flowered families of which the Compositae represent the most elaborate type.
Anton Kerner has shown that crowded inflorescences such as those of Compositae and Umbelliferae are especially adapted for geitonogamy.
Climbing plants with gorgeous flowers are common, and there are numerous species of Compositae and about a hundred cinchonaceous plants.
Compositae are comparatively rare; so also Gramineae and Cyperaceae are in some places deficient, and Labiatae, Leguminosae and ferns in others.
Compositae compose a quarter of the Andean flora, which is a greater proportion than in any in the world.
Ethylene succinic acid occurs in amber, in various resins and lignites, in fossilized wood, in many members of the natural orders of Papaveraceae and Compositae, in unripe grapes, urine and blood.
In Compositae besides the involucre there are frequently chaffy and setose bracts at the base of each flower, and in Dipsacaceae a membranous tube surrounds each flower.
In Compositae the name involucre is applied to the bracts surrounding the head FIG.
In number of species Gramineae comes considerably after Compositae and FIG.
In the capitula of Compositae we sometimes find the florets converted into green leaves.
In the central parts of the same table-land huge thisties (such as the Onopordum nervosunl), centaureas, artemisias and other Compositae are scattered in great piof usion.
In these districts and others the number has become much reduced, owing doubtless in part to the fatal practice of catching the birds just before or during the breeding-season; but perhaps the strongest cause of their growing scarcity is the constant breaking-up of waste lands, and the extirpation of weeds (particularly of the order Compositae) essential to the improved system of agriculture; for in many parts of Scotland, East Lothian for instance, where goldfinches were once as plentiful as sparrows, they are now only rare stragglers, and yet there they have not been thinned by netting.
In tropical regions, where Leguminosae is the leading order, grasses closely follow as the second, whilst in the warm and temperate regions of the northern hemisphere, in which Compositae takes the lead, Gramineae again occupies the second position.
It sometimes bears hairs, which aid in the application of the pollen to the stigma, and are called collecting hairs, as in Campanula, and also in Aster and other Compositae.
Occasionally some of the petals become more united than others, and then the corolla assumes a bilabiate or two-lipped form, as seen in the division of Compositae called Labiatiflorae.
Of this genus of Compositae, few save B. rubra, the Red Hawks-beard, are worthy of culture.
Other characteristic features of the flora are the abundance of Compositae, Asclepiadeae, and petaloid Monocotyledons generally, but especially Orchideae (terrestrial species predominating) and Iridaceae.
Plants of the same order as the Daisy (Compositae), of which some three or four forms are in cultivation.
So large a proportion of the trees still belongs to the flora of North America that one is apt to overlook the fact that among the more specialized plants some of the largest American orders, such as the Compositae, are still missing from strata belonging to the Cretaceous period.
Such are Compositae as a class, also Scabiosa, Armeria (sea-pink) and others.
The Compositae are represented by isolated fruits of various species.
The former, which is a somewhat less favourable method than the latter, is effected by air-currents, insect agency, the actual contact between stigmas and anthers in neighbouring flowers, where, as in the family Compositae, flowers are closely crowded, or by the fall of the pollen from a (From Darwin's by permission.) FIG.
The limb of the calyx may appear as a rim, as in some Umbelliferae; or as pappus, in Compositae and Valeriana.
The moist soil encourages luxuriant thickets of willows (Salicineae), surrounded by dense chevaux-de-frise of wormwood and thornbearing Compositae, and interspersed with rich but not extensive prairies, harbouring a great variety of herbaceous plants; while in the deltas of the Black Sea rivers impenetrable beds of reeds (Arundo phragmites) shelter a forest fauna.
The most numerously represented family is the Compositae, the grasses being next in number.
The orders most abundantly represented are the Compositae, Cruciferae, Labiatae, Caryophyllaceae and Scrophulariaceae.
The second subclass, Gamopetalae, includes 9 series and culminates in those which show the most elaborate type of flower, the series Aggregatae, the chief representative of which is the great and wide-spread order Compositae.
Though the fondness of this species for the seeds of flax (Linum) and hemp (Cannabis) has given it its common name in so many European languages,' it feeds largely, if not chiefly in Britain on the seeds of plants of the order Compositae, especially those growing on heaths and commons.
When there is a single ovule, with its axis vertical, it may be attached to the placenta at the base of the ovary (basal placenta), and is then erect, as in Polygonaceae and Compositae; or it may be inserted a little above the base, on a parietal placenta, with its apex upwards, and then is ascending, as in Parietaria.