plants with which it is associated for the purpose of establishing a connexion with the Equisetine ferns, and not abruptly passing from one section to another. The port of these trees is very remarkable, and especially that of C. equisetifolia,

A. Casuarina quadrivalvis. (a) Branchlet enlarged, to shew the nodi, vaginæ, and internodia. (b) Spiciform ament of monandrous flowers. (c) Strobiliform fruit when ripe. (d) Section of the same. (e) One carpel isolated. (f) Two whorls from the stamineous ament, to shew the exsertion of the stamens. (g) Strobiliform ament of pistilline flowers. (h) Section of the same. (i) A pistilline flower

isolated.

which rises to the height of fifteen feet and upwards, and spreads its main branches freely on every side, from which hang down their finer divisions in bunches like horsetails. The branches and branchlets are articulated throughout, with sheaths surrounding the articulations, and the intermediate spaces grooved or striate, which characters (so much a repetition of Equisetum,) distinguish this type, called the Casuarinacea, from the Myricacea, the following group, often associated with it.

(1511.) The Casuarina are peculiarly interesting plants, as forming the transitional series from the Pineales to the present order. Until the ovules of the Pinares were shewn to be naked, and those of the Casuarina invested with pericarps, these plants were sometimes associated with the Amentaceæ, which they resemble in their mode of inflorescence; and at others with Ephedra, to which, by their leafless articulate branches, they bear no slight similitude. Indeed, the analogy is perfect between both these genera, which, with Equisetum of the ferns, form one of those extraordinary osculations in which plants essentially diverse in their organs of fructification exhibit a strong resemblance in other particulars; and,

were it not that the Equiseta are flowerless, the Ephedra naked-seeded, and the Casaurine anglospermous plants, their articulated branches, destitute of leaves, would have seemed to indicate their union as an order.

(1513.) The Casuarinacea are much branched trees, with verticillate branchlets, the nodi disarticulating as in Equisetum, and surrounded by many-cleft or toothed vaginæ, from within which the successive shoots arise; the internodia are grooved and striated.

The flowers are separate, either monacious or diœcious, and collected into terminal spiciform aments. The stamineous flowers are surrounded with manytoothed vaginæ, the perianth (?) four-leaved and chaffy; the stamen solitary, filament awl-shaped, anther erect and two-celled, dehiscing by a longitudinal chink; the connectivum obsolete.

The pistilline flowers are crowded into dense subovate spikes, or aments, the articulation being obsolete, and the perianth wanting.

The germen is lenticular, the ovule solitary, erect, and with a foramen at its apex. The styles two, and inferiorly connate. The fruit is winged, invested with thickened bracteole; the seed solitary, erect, and exalbuminous; and the embryo inverted.

(1514.) Differentially considered, the Casuarinaceæ are angiospermous exogenæ, with articulate leafless branches; amentaceous flowers, free germen, solitary erect ovules, and exalbuminous seeds.

(1515.) The Casuarina are chiefly Australian plants; thirteen species are known, six of which have monœcious, and seven diœcious flowers. The wood of several is hard and dense, and may probably become valuable in the market as timber; hitherto, however, it has been but little used except by the natives to form their clubs and other warlike weapons, for which, by its density and hardness, it is peculiarly adapted. Ainslie states that the C. equisetifolia is astringent, and is administered medicinally by the Javanese. This species was introduced by the first Lord Byron.

(1516.) Casuarina is the only known genus belonging to the type, but so peculiar is its structure, that it would be abnormal, if combined even with its nearest allies.

(1517.) MYRICACER. The Gales and candleberry-myrtles, so called from their waxy exudations, which, when collected, are made into soap and candles, are well-known plants both in Europe, Africa, and America; and are associated with their immediate allies, Comptonia and Nageja, to form the present type.

(1518.) The Myricaceae are either shrubs or trees, with round scattered exarticulate branches, the leaves alternate, simple, or pinnatifid, with or without stipulæ, penninerved, and for the most part entire, though sometimes serrate. The flowers are monœcious or diœcious, and collected into aments. The stamina are two or more, arising from the axillæ of a single hypogynous scale, the filaments are free or monadelphous, and the anthers two-celled.

The pistilline flowers are surrounded by several hypogynous scales. The germen is free, lenticular, and one-celled, and the ovule solitary. The style single, and the stigmata two, long, and filiform. The pericarp is dry and indehiscent, membranous, and winged at the edges; sometimes falsely drupaceous, from the scales with which it is covered becoming succulent and fleshy. The seed is

erect and exalbuminous, and the embryo, which is large, inverted, the short radicle being superior.

Myrica arguta.

c. Branch, shewing the alternate leaves and amentaceous flowers.

(a) Stamineous flower separated, shewing its bractea and monadelphous filaments.

(b) Pistilline flower, with its hypogynous scales and two filiform stigmata.

(c) The fruit.

(d) The calycine leaflet.

(e) Section of the fruit, shewing its winged edges and erect seed.

(f) The seed.

(g) The embryo denuded.

(1519.) Differentially considered, the MYRICACER are Quercina, or amentaceous exalbuminous QUERNEALES with foliose exarticulate branches, one-celled ovaries, and erect solitary ovules.

(1520.) The Myricacea are both astringent and aromatic. Our common sweet gale (M. Gale) is prized by country people for its agreeable odour. It is also said to be inimical to vermin, and hence its use in decoctions to destroy fleas, and other similar pests of the body and the bed; as well as to cure the itch. An infusion has also been recommended as a vermifuge. Myrica sapida bears a fruit about the size of a small plum, having a pleasant refreshing subacid taste, and, according to Buchanan, it is eaten in Nepal. The root of M. cerifera is a powerful astringent, but it is more prized for the wax it bears than as a medicine; and in some parts of North America, where animal tallow is scarce, its annual crop of wax is collected and made into candles. Our common gale yields wax, but much less abundantly.

Comptonia asplenifolia is both tonic and astringent, and a decoction of it is a favorite domestic remedy, in the United States, for the cure of diarrhoea.

(1521.) SALICACEE. The willows (Salices), and poplars (Populi), form, together, a very extensive type as regards species, although containing two genera only, which are distinguished from each other by the inferior radicle of salix, and the superior radicle of populus, as well as by the gland at the base of the onecelled follicle of salix, while the follicle of populus is almost two-celled, and without a gland. United as a type the Salicacea are known from the contingent group, especially from Betulacea, the only one with which it is likely to be con

founded, by the indefinite erect ovules, those of Betulaceae being pendulous and definite; as well as by the seeds of the Salicaceae being crowned with silky tufts, while those of the Betulaceæ are naked.

A. Salix caprea.

(a) Branch with pistilline aments. (b) Ditto, with stamineous ones. (c) Single stamineous flower, shewing its two naked stamina, arising from the axilla of the bractea or scale, in which there is also seen the abortive pistil. (d) The perfect pistilline flower with the abortive stamina. (e) Section of the ovary, to shew the many seeds. (f) A seed with its down.

B. Quercus navalis vel pedunculata.-Branch to shew the peduncled acorns and sessile leaves. (a) Pistilline flowers in an early stage. (b) Stamineous aments. (c) Stamineous flower isolated. (d) Pistilline flower isolated, shewing the cupule and rudimentary superior calyx. (e) Gland without the cupule. (f) Longitudinal division shewing one large cotyledon of the exalbuminous embryo.

c. Juglans regia. Branch shewing fruit and pinnate leaves. (a) Staminiferous ament. (6) Longitudinal section of a pistilline flower. (c) Longitudinal section of the ripe fruit, shewing the exocarp, mesocarp, and endocarp, the radicle, plumule, and one of the cotyledons of the exalbuminous embryo. (d) Transverse section of the fruit, shewing the two wrinkled cotyledons. (e) The seed detached.

(1522.) The Salicacea are shrubs or trees, often of a large size, with round and scattered branches. The leaves are alternate, simple, and stipulate, the stipula being free and caducous, or leaf-like and persistent, [§ 1521, A.]

The foliar margins are serrate or crenate, and the costulæ deliquescent. Foliar glands are often, but not universally present.

The flowers are separated, either monoecious, or more frequently diœcious; and collected into cylindrical or ovate catkins. The stamineous ones consist of stamina, from two to twenty-four in number, free or monadelphous, with erect

two-celled anthers, dehiscing by longitudinal chinks, and arise from a glandular torus situated in the axilla of a squamaceous bracte. The pistilline flowers are achlamydeous, and consist of a fusiform germen with two styles, often connate, and terminated by emarginate or bipartite stigmata. The ovary is superior, one-celled or sub-bilocular, from the margins of the valves becoming introflexed. The trophosperms are two, parietal, and many-ovuled; and the ovules erect.

The fruit is a one or two celled, oblong, coriaceous capsule, two-valved and dehiscing downwards. The seeds are many, and attached to the lower part of the cell, exalbuminous and comose. The embryo is straight, and the radicle inferior. (1523.) Hence, differentially considered, the Salicace are achlamydeous Quercine with indefinite comose seeds, [§ 1521, a.]

(1524.) The willows are extremely useful plants, and afford, from wet and swampy soil, where few other trees will flourish, oziers for basket-making, bark for tanning, and a peculiar alkaloid named salicine, which appears likely to rival the Quinine of Peruvian bark, in the successful treatment of intermittent fevers. S. caprea, fragilis, and alba, are those chiefly esteemed for their febrifuge properties, but the bark of most of the species is astringent and tonic. Sir Humphry Davy found willow-bark to contain as much tanning principle as that of the oak; the species in which it is most abundant are S. Russelliana, alba, and purpurea, the latter of which is the toughest of all the willows.

Salix herbacea is the smallest tree existing; it varies from one to three inches in height; its leaves are used in Iceland for tanning leather.

(1525.) The known species of willow amount to nearly 200, the majority of which have been figured by the Duke of Bedford, in his Salictum Woburnense; and it is greatly to be deplored that so few copies of that splendid work were printed, and more especially, as of all genera the species of this are perhaps the most difficult of distinction.

(1526.) S. alba is the most valuable of the whole as a timber-tree, and, when pollarded, is very productive of poles, fence-wood, crate-ware, and fuel.

S. viminalis, vitellina, and others, are cultivated in swampy districts under the name of osiers, and their use for basket-work, hoops, &c. is well known. They are remarkably quick growing plants, whence indeed their generic name.

(1527.) Willows are much used in the manufacture of charcoal; and it has been proved that willow-charcoal is superior to that of most other wood for the preparation of gunpowder. Before the introduction of coke into our iron-works, such immense quantities of wood were annually converted into charcoal, that Evelyn, in his Sylva, expressed a fear that the demands of the furnaces would lead to the entire destruction of our forests. Indeed, the Forest of Dean was almost wholly consumed in the reduction of the iron ore that abounds in its locality. Even in 1788, twenty-six out of the eighty-six iron furnaces then at work in England, were heated by wood-charcoal; but in 1826, the three hundred and five, to which they had increased, were all fed by pit-coal coke.

(1528.) The weeping willow, (S. Babylonica,) which is the most ornamental species, has received its specific name from the supposition that it was upon such trees that the Israelites hanged their harps, when by the waters of Babylon they sat down and wept on the remembrance of Sion. But modern travellers affirm that it is a mountain-plant, and not an aquatic one. Pope's willow, at Twickenham, which was sacrilegiously cut down a few years ago, was the parent of many