MORETON BAY CHESTNUT, a tall tree known botanically as Castanospermum australe (natural order Leguminosae), native of Queensland and New South Wales.
Fixation of Nitrogen.Another, and perhaps an even more important, instance of symbiotic association has come to the front during the same period, it is an alliance between the plants of the Natural Order Leguminosae and certain bacterium-like forms which find a home within the tissues of their roots.
Many writers in recent years, among whom may be named especially Heliriegel and Wilfarth, Lawes and Gilbert, and Schlcesing and Laurent, have shown that the Leguminosae as a group form conspicuous exceptions to this rule.
The power exercised by the Leguminosae is associated with the presence of curious tubercular swellings upon their roots, which are developed at a very early age, as they are cultivated in ordinary soil.
In India proper, with a dryer climate, grasses and Leguminosae take the lead in the number of species.
Amongst arboreous families Leguminosae and Euphorbiaceae are prominent; Hevea belonging to the latter is widely distributed in various species in the Amazon basin, and yields Para and other kinds of rubber.
The most dominant order in Australia is Leguminosae, including the acacias with leaf-like phyllodes (absent in New Zealand).
The principal orders, arranged according to their numerical importance, are as follows: - Leguminosae,Rubiaceae, Orchidaceae, Compositae, Gramineae, Euphorbiaceae, Acanthaceae, Cyperaceae and Labiatae.
Compositae are comparatively rare; so also Gramineae and Cyperaceae are in some places deficient, and Labiatae, Leguminosae and ferns in others.
The chief trees belong to the orders of Terebinthaceae, Sapindaceae, Meliaceae, Clusiaceae, Dipterocarpaceae, Ternstroemiaceae, Leguminosae, laurels, oaks and figs, with Dilleniaceae, Sapotaceae and nutmegs.
The arboreous forms which least require the humid and equable heat of the more truly tropical and equatorial climates, and are best able to resist the high temperatures and excessive drought of the northern Indian hot months from April to June, are certain Leguminosae, Bauhinia, Acacia, Butea and Dalbergia, Bombax, Shorea, Nauclea, Lagerstroemia, and Bignonia, a few bamboos and palms, with others which extend far beyond the tropic, and give a tropical aspect to the forest to the extreme northern border of the Indian plain.
The more common plants in the most characteristic part of this region in southern Arabia are Capparidaceae, Euphorbiaceae, and a few Leguminosae, a Reseda and Dipterygium; palms, Polygonaceae, ferns, and other cryptogams, are rare.
Peculiar forms of Leguminosae also prevail, and these, with many of the other plants of the southern and drier regions of Siberia, or of the colder regions of the desert tracts of Persia and Afghanistan, extend into Tibet, where the extreme drought and the hot (nearly vertical) sun combine to produce a summer climate not greatly differing from that of the plains of central Asia.
Another plant of the same family (Leguminosae) Hedysarum coronarium, a very handsome hardy biennial often seen in old-fashioned collections of garden plants, is commonly called the French honeysuckle.
It is a member of the natural order Leguminosae, largely cultivated as a pulse-food in the south of Europe, Egypt and western Asia as far as India, but is not known undoubtedly wild.
This tree belongs to the natural order Leguminosae, sub-order Papilionaceae.
ACACIA, a genus of shrubs and trees belonging to the family Leguminosae and the sub-family Mimoseae.
In the tropical zone large figs abound, Terminalia, Shorea (sal), laurels, many Leguminosae, Bombax, Artocarpus, bamboos and several palms, among which species of Calamus are remarkable, climbing over the largest trees; and this is the western limit of Cycas and Myristica (nutmeg).
On the drier and higher mountains of the interior of the chain, the forests become more open, and are spread less uniformly over the hill-sides, a luxuriant herbaceous vegetation appears, and the number of shrubby Leguminosae, such as Desmodium and Indigofera, increases, as well as Ranunculaceae, Rosaceae, Umbelliferae, Labiatae, Gramineae, Cyperaceae and other European genera.
The work of numerous observers has shown that the free nitrogen of the atmosphere is brought into combination in the soil in the nodules filled with bacteria on the roots of Leguminosae, and since these nodules are the morphological expression of a symbiosis between the higher plant and the bacteria, there is evidently here a case similar to the last.
That the Leguminosae (a group of plants including peas, beans, vetches, lupins, &c.) play a special part in agriculture was known even to the ancients and was mentioned by Pliny (Historia Naturalis, viii.).
They showed that, when grown on sterilized sand with the addition of mineral salts, the Leguminosae were no more able to use the atmospheric nitrogen than other plants such as oats and barley.
Leguminosae, the two most numerous orders of phanerogams, but in number of individual plants it probably far exceeds either; whilst from the wide extension of many of its species, the proportion of Gramineae to other orders in the various floras of the world is much higher than its number of species would lead one to expect.
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.