ACACIA (from ac, a point, in Celtic; or from akazo, to sharpen; many of the species are furnished with spines). See also [Albizzia]. ORD. Leguminosæ. Shrubs or trees, 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 unquestionably 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 require is copious waterings, never allowing them to become dry, and keeping clear of weeds. In the first week in October house the plants, and winter in a temperature of 40deg. to 50deg. 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 ¼in. 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. 5ft. 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 pinnæ, each pinna bearing nineteen to twenty-two pairs of oblong linear-leaflets. h. 5ft. Swan River.
A. amœna (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 pinnæ, 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).* Gum Arabic. fl. white; heads pedunculate, axillary, usually in threes. l. with four to six pairs of pinnæ, each pinna bearing ten to twenty pairs of oblong-linear leaflets. h. 20ft. Arabia, East Indies, &c., 1820. Greenhouse species. See Fig. 4.
A. argyrophylla (silver-leaved). A synonym of A. brachybotrya.
A. armata (armed, simple leaved).* fl. yellow, in solitary globular heads. April. l. phyllodia obliquely ovate-oblong, quite entire, one-nerved. h. 6ft. to 10ft. Australia, 1803.
A. Benthami (Bentham's). A synonym of A. cochlearis.
A. brachybotrya (short-bunched).* fl. yellow, in axillary stalked globular heads. April. l. phyllodia silvery silky, obliquely obovate, or oblong. h. 8ft. Swan River. SYN. A. argyrophylla.
A. Catechu (catechu). fl. yellow; spikes cylindrical, solitary, twin, or tern, axillary. March. l. with ten pairs of pinnæ, each of which bears forty to fifty pairs of linear pubescent leaflets. h. 20ft. to 40ft. East Indies, 1790.
A. cavenia (Cavenia).* fl. yellow, disposed in globose heads, peduncles, axillary, aggregate. l. with usually about five pairs of pinnæ, each of which bears nine to ten pairs of linear-oblong leaflets, clothed with scabrous pubescence. h. 20ft. Chili. Greenhouse species.
A. cochlearis (spoon-leaved). fl. yellow, in solitary globular heads. April. l. phyllodia linear lanceolate, many-nerved at the base, quite entire, mucronate. h. 4ft. West Australia, 1818. SYN. A. Benthami.
A. cultriformis (knife-formed).* fl. yellow, in crowded heads, disposed in either axillary or terminal racemes. April. l. phyllodia eight to ten lines long, four lines broad, cultriform, ending in an acute hooked point, which bears to one side. h. 4ft. New South Wales, 1820.
A. cuneata (wedge-shaped).* fl. yellow. April. Swan River, 1837. Greenhouse species.
A. cyanophylla (blue-leaved). fl. yellow; racemes axillary; heads globose. March. l. phyllodia lanceolate, often 1ft. long, glaucous green, almost blue; branches drooping. h. 18ft. Swan River, 1838. Arboreous.
A. dealbata (whitened).* The Silver Wattle. fl. yellow, in pedicellate heads, disposed in racemes along the axillary branches. July. l. from ten to twenty pairs of pinnæ, each of which bears thirty to thirty-five pairs of linear, much crowded pubescent leaflets. h. 10ft. to 20ft. Australia and Tasmania, 1820.
A. diffusa (spreading). fl. yellow, in globular heads, which are usually twin. May. l. phyllodia linear, one-nerved, ending in an oblique acumen; branches diffusely procumbent, angular. h. 2ft. Victoria and Tasmania, 1814.
A. Drummondi (Drummond's).* fl. pale lemon; spikes axillary, drooping, cylindrical, simple. April. l. with two pairs of pinnæ, each pinna bearing two to three pairs of linear obtuse leaflets. Plant unarmed, silky. h. 10ft. Swan River. Very handsome and one of the best grown, forming a somewhat dwarf shrub.
FIG. 4. ACACIA ARABICA (a) Flowering Branch, (b) Seed-pod.
A. Farnesiana (Farnesian). fl. yellow, sweet-scented, disposed in axillary, usually twin, unequally pedunculate heads. July. l. with five to eight pairs of pinnæ, each pinna bearing from fifteen to twenty pairs of linear glabrous leaflets. h. 6ft. to 10ft. St. Domingo, 1656. Greenhouse species.
A. glauca (milky white).* fl. white; spikes globose, stalked, axillary, usually twin. July. l. with four to six pairs of pinnæ, each pinna bearing about twelve to fifteen pairs of linear, distant, acute leaflets, which are glaucous beneath. h. 5ft. to 10ft. South America, 1690.
A. glaucescens (greyish). fl. yellow; spikes twin, but solitary on the peduncles, axillary. June. l. phyllodia linear-lanceolate, attenuated at both ends, falcate, three-nerved. h. 6ft. to 8ft. Queensland, 1822. SYN. A. homomalla.
A. grandis (great).* fl. yellow; heads globular; peduncles solitary or twin, axillary, one-headed. February to May. l. with one pair of pinnæ, each pinna bearing eight to ten pairs of linear-lanceolate leaflets; branches hairy. h. 6ft. West Australia, 1850. A variety of A. pulchella.
A. heterophylla (variable-leaved).* fl. yellow, in heads, disposed in a kind of raceme. May. l. phyllodia linear, attenuated at both ends, many-nerved. h. 5ft. Isle of Bourbon, 1824. A. amœna is very like this.
A. hispidissima (hairiest). A variety of A. pulchella.
A. holosericea (all silky). fl. yellow, in axillary spikes, usually twin. May. l. 6in. long, oblong-lanceolate, ending in a soft point at the apex, three-nerved. h. 10ft. to 20ft. Australia, 1818. The whole aspect of this tree is silky. SYN. A. leucophylla.
A. homomalla (equal-woolled). A synonym of A. glaucescens.
A. Hugelii (Baron Hugel's). fl. pale yellow. February. West Australia, 1846. Greenhouse species.
A. ixiophylla (Ixia-leaved). fl. yellow; heads about twenty-flowered; peduncles downy, shortly racemose or solitary. March. l. narrow, oblong-lanceolate, sub-falcate, obtuse, obliquely mucronate, much branched. h. 2ft. New South Wales, 1844.
A. juniperina (juniper-leaved). fl. yellow, in solitary heads. May. l. linear-subulate, ending in a pungent point; branches terete, pubescent. h. 6ft. Australia and Tasmania, 1790. Greenhouse.
A. Lebbek (Lebbek).* fl. yellow, sweet-scented; heads many-flowered, pedunculate, three or four together, from the crowded upper nodes. May. l. with two to four pairs of pinnæ, each pinna bearing about six to eight pairs of oval, somewhat dimidiate leaflets, which are obtuse at both ends. h. 20ft. East and West Indies, 1823. Stove species.
A. leprosa (leprous). fl. yellow, mostly five-parted, numerous in a globular head; peduncles mostly in pairs or clusters, ¼in. long. May. l. narrow, linear-lanceolate, acute or obtuse with a small callous point, narrowed at base, 1½in. to 3in. long, those of the barren shoots broader. Branchlets pendulous, more or less glutinous. Australia, 1817. (B. R. 1441.)
A. leucophylla (white-leaved). A synonym of A. holosericea.
A. lineata (lined). fl. yellow, mostly five-parted, ten to fifteen or rarely more in a small, globular head; peduncles slender, rarely exceeding the leaves. April. l. linear, with a small hooked point, about ½in., rarely ¾in., long, one-nerved. Branches nearly terete, usually pubescent or villous. h. 6ft. Australia, 1824. (B. M. 3346.)
A. l. longissima (longest). Synonymous with A. longissima.
A. longifolia (long-leaved).* fl. yellow; spikes loose, axillary, cylindrical. March. l. phyllodia linear-lanceolate, narrowed at each end, three-nerved, striated. h. 10ft. Australia, 1792. A fine erect-growing greenhouse species.
A. longissima (longest-leaved). fl. yellow; spikes several, axillary, generally branched. May. l. phyllodia very long, filiform, one-nerved, spreading. h. 4ft. New South Wales, 1819. Stove species. SYN. A. linearis longissima.
A. lunata (half-moon).* fl. yellow; heads disposed in racemes, which are longer than the phyllodia. April. l. phyllodia obliquely oblong, rather falcate, narrowed at the base, terminating in an oblique callous mucrone. h. 2ft. to 4ft. Australia, 1810. Greenhouse species. SYN. A. oleæfolia.
A. melanoxylon (black wooded). fl. yellow; heads few, disposed in a kind of raceme. April. l. phyllodia lanceolate-oblong, rather falcate, obtuse, quite entire, many-nerved. h. 6ft. to 10ft. Australia, 1818. Greenhouse species.
A. mollissima (softest-leaved).* fl. yellow; heads pedicellate, disposed in racemes along the axillary peduncles. July. l. with eight to eighteen pairs of pinnæ, each pinna bearing thirty to forty pairs of linear, much crowded, pubescent leaflets, which are clothed with yellowish velvety down when young; branches and petioles angular. h. 10ft. to 20ft. Van Diemens Land, 1810.
A. oleæfolia (olive-leaved). A synonym of A. lunata.
A. oxycedrus (sharp-cedrus).* fl. yellow; spikes axillary, solitary, elongated. April. l. phyllodia scattered, or somewhat verticillate, lanceolate-linear, ending in a pungent point, three-nerved. h. 6ft. to 10ft. New South Wales, 1823. Greenhouse species.
A. paradoxa (paradoxical). fl. yellow, disposed in solitary heads. March. l. phyllodia obliquely oblong-lanceolate, entire, wavy, one-nerved; branches clammy, glabrous. h. 6ft. New Holland. Greenhouse species.
A. penninervis (feather-nerved). fl. yellow; heads about the size of a pea, racemose. April. l. phyllodia oblong, acuminated at both ends, straight, 2in. to 3in. long, ½in. broad, feather veined. h. 4ft. to 6ft. New Holland, 1824.
A. platyptera (broad-winged).* fl. yellow; heads solitary, on short peduncles. March. l. phyllodia short, bifarious, decurrent, obliquely truncate, mucronate; branches broadly winged. h. 3ft., Swan River, 1840. Greenhouse species.
A. pubescens (downy).* fl. yellow; heads small, globose pedicellate, disposed in racemes along the axillary peduncles. March. l. with three to ten pairs of pinnæ, each pinna bearing six to eighteen pairs of linear glabrous leaflets. h. 6ft. to 10ft. Branches terete, hairy. New Holland, 1790.
A. pulchella (pretty).* fl. yellow; heads solitary. April. l., pinnæ bearing five to seven pairs of oblong-ovate, obtuse leaflets. h. 2ft. to 3ft. New Holland, 1803. Greenhouse species. The variety hispidissima has white flowers.
A. Riceana (Rice's).* fl. pale yellow, in long, solitary, axillary spikes. May. l. linear, in clusters, dark green, scattered or whorled. h. 20ft. Tasmania. Habit graceful, like a weeping willow. Very handsome and distinct. SYN. A. setigera. See [Fig. 5.]
A. rotundifolia (round-leaved). fl. yellow; heads globose, solitary, on long peduncles. March. l. phyllodia on short petioles, obliquely rounded, obtuse or retuse, mucronate. Branches angular, puberulous. h. 6ft. New Holland, 1842.
A. saligna (willow-like). fl. yellow; heads solitary, on short peduncles. March. l. phyllodia linear, attenuated at both ends, quite entire, almost nerveless. h. 6ft. to 10ft. New Holland, 1818. Greenhouse species.
A. Senegal (Senegal). Gum Senegal. fl. white, small, glabrous, distant; spikes axillary, solitary, slender. l. with five to eight pairs of pinnæ, each pinna bearing fifteen to eighteen pairs of oblong-linear, obtuse, glabrous leaflets; branches white; prickles sometimes wanting. h. 20ft. Arabia, 1823. Stove species.
A. setigera (bristly). Synonymous with A. Riceana.
A. sophoræ (sophora-podded). fl. yellow; spikes usually twin, axillary. May. l. phyllodia obovate, oblong or lanceolate, quite entire, many nerved; sometimes there are bipinnate leaves at the tops of the branches. h. 20ft. New Holland, 1805.
A. sphærocephala (round-headed).* fl. yellow; racemes axillary, usually twin, ovate-roundish. l. with numerous close-set linear falcate pinnules, which are usually tipped by a glandular yellow "food body;" spines twin, hollow. Mexico. A very remarkable stove species, inhabited by ants during certain seasons in its native country.
A. uncinifolia (hook-leaved). fl. yellow; spikes usually twin, dense, on short peduncles, cylindrical. March. l. phyllodia long, linear-subulate, flat, recurved, mucronate, three-nerved; branches angular. h. 6ft. Swan River, 1846.
A. vera (true). Egyptian Thorn; Gum Arabic. fl. white, usually in twin heads, pedunculate, axillary. July. l. with two pairs of pinnæ, each pinna bearing eight to ten pairs of oblong linear leaflets; branches and spines red. h. 20ft. Egypt, 1596.
FIG. 5. A FLOWERING BRANCH OF ACACIA RICEANA.
A. verticillata (whorl-leaved).* fl. yellow; spikes axillary, solitary, oblong. March. l. phyllodia linear, ending in a pungent mucrone, disposed somewhat verticillately. h. 6ft. to 10ft. A spreading, prickly, greenhouse species, of variable habit. New Holland, 1780.
A. vestita (clothed).* fl. yellow, in loosely racemose heads, along the peduncles; upper ones solitary. June. l. phyllodia obliquely elliptic-lanceolate, one-nerved, ending in an awnlike mucrone, hispid. h. 4ft. New Holland, 1820.
A. viscidula (clammy).* fl. yellow; heads globular, on short stalks, axillary, solitary or twin. February. l. linear, clammy; branches slender, clammy. h. 6ft., erect. New South Wales, 1844.
ACÆNA (from akaina, a thorn; in allusion to the slender spines on the calyx or fruit). ORD. Rosaceæ. A genus of dwarf sub-shrubby plants. Flowers capitate, or interruptedly spicate, uninteresting; petals absent. Leaves alternate, impari-pinnate. Excepting for rockwork, or as edgings to flower beds, they are not of much value; their habit is, however, very compact and neat. They require similar treatment to other hardy herbaceous plants, in ordinary soil. Increased by cuttings, creeping rootlets, divisions, and by seeds.