Acacia
(from ac, a point, in Celtic; or from akazo, to sharpen; many of the species are furnished with spines). See also Albizzia. ORD. Leguminosae. Shrubs or three, very variable in habit and leaves. Flowers yellow, white, rarely red, disposed in globular heads or spikes, decandrous or polyandrous. Spines stipular, scattered, or wanting. This is a very polymorphous genus, and the majority of species described are known in this country only from herbarium specimens. It is very doubtful whether the entire genus is represented in our gardens by more than about fifty species, many of which are only to be found in botanic gardens; but this number is, without doubt, sufficiently characteristic. The number of species is close upon 400, and the genus one of the largest known. In our enumeration, we have strictly confined ourselves to describing such as are questionably in cultivation, and to this end we have adopted the only accurate method of deciding which are and which are not grown, viz., by consulting the trade lists of nurserymen, both in this country and on the Continent. Such lists, however, are not always correct, from a scientific point of view, in the matter of nomenclature. The species best deserving of cultivation are all natives of Australia, New South Wales, or other temperate regions, and are among the hardiest and most easily cultivated of all greenhouse plants. They are very floriferous. The greenhouse species are sufficiently hardy to withstand the winter in a temperature very little higher than freezing point Cultivation: Some have a tendency to make long straight shoots; these should be selected for training upon rafters or pillars, on which they thrive well and form splendid ornaments in spring; whilst the more shrubby kinds will be equally at home in pots in the form of bushes. Roots and tops grow with great rapidity, and an abundance of water is required at all times. Immediately after flowering (usually about May) is the best time to prune Acacias; they may then be placed in the open air, and fully exposed to the sun, until October. They make a far healthier, cleaner growth, and ripen their wood much better outside than under glass; all they requires is copious waterings, never allowing them to become dry, and keeping clear of weeks. In the first week in October house the plants, and winter in a temperature of 40dge. To 50dge. They delight in a light rich compost of equal parts turfy loam and leaf mould, freely intermixed with sand, or peat may be used instead of the leaf mould. Propagation: Cuttings of the half-ripened wood, put in with a heel, root readily during the summer. They do not bear heat well, nor do they require it. The soil should be equal parts peat and sand, covered with pure sand, thoroughly consolidated. Insert the cuttings as soon as made; water home, and leave them in the shade till dry. Then place the bell glasses over them, shade and water so as to prevent flagging. Pot off as soon as rooted, and keep in a close pit or house until the plants are thoroughly established. Seeds should be sown as soon as ripe, in sandy peat; about 1/4in. deep, or a little more, for large seeds. A temperature of 55deg. To 60deg. Suits them well. Pot off when large enough to handle, and place in a cool close pit or house until quite established. The culture and propagation of the stove species are the same as for the greenhouse sorts, but the former require, of course, greater heat. Their flowers, however, are much less frequently produced than their more temperate congeners, consequently they are not so much grown.
A. affinis.* fl. yellow. May, h. 5th. New Holland, 1822. Greenhouse species. A. albicans (whitish).* fl. white; heads, two to five, aggregate, rising in racemes from the axils to the leaves. l. with eight to nine pairs of pinnae, each pinna bearing nineteen to twenty-two pairs of oblong linear-leaflets. h. 5th Swan River.
A. amoena (pleasing). This closely resembles A. heterophylla. A. angustifolia (narrow-leaved). fl. yellow, in heads two to four together, pedunculate. April. l. with fifteen to twenty pairs of pinnae, each pinna bearing thirty to forty pairs of linear-acute, ciliated leaflets. h. 4ft. New South Wales, 1816. One of the numerous varieties of A. longifolia. A. arabica (Arabian).* Gun Arabic. fl. white; heads pedunculate, axillary, usually in threes. l. with four to six pairs of pinnae, each pinna bearing ten to twenty pairs of oblong-linear leaflets. h. 20ft. Arabia, East Indies, &c., 1820. Greenhouse species.
A. argyrophylla (silver-leaved). A synonym of A. brachybotrya. A. armata (armed, simple leaved).* fl. yellow, in solitary globular heads.