Endógenes, or Monocotyledonous plants, are the first remove from Cellulares, and hold an intermediate rank between them and Exógenes or Dicotyledonous plants, in which vegetation acquires its highest form of developement. They were formerly characterised by having a single cotyledon, but this circumstance is not only not absolute, but difficult of determination, except after minute analysis. The real difference between their seed and that of Dicotylédones is this, that in Monocotylédones there is only one cotyledon (fig. 11. s), or, if two, that they are alternate with each other (fig.11. t), while in Dicotylédones they are always opposite, and more than one, sometimes several, as in Pìnus. (fig. 12. y.) The physiological structure of the two classes is, however, that by which they are familiarly distinguished, and exhibits a beautiful proof of the harmony that exists between the great features of vegetation and their first principle, the seed from which they originate. In Endógenes or Monocotylédones there is no distinction between wood and bark (fig. 11. q); in Exógenes or Dicotylédones, the wood and bark are distinctly separated. (fig. 12. v.) In Monocotylédones the wood and cellular tissue are mixed together, without any distinct annual layers of the former being evident; in Dicotylédones the wood and cellular tissue have each their particular limits assigned them, a distinct layer of the former being annually deposited. In Monocotylédones there are no radiations from the medulla to the bark; in Dicotylédones the radiations are distinctly marked. In Monocotylédones there is generally no articulation between the leaves and the stem, while in Dicotylédones the leaves are always jointed with the stem from which they fall off, leaving a scar behind. In Monocotylédones the veins of the leaf pass in parallel lines

from the base to the apex, in Dicotylédones they diverge from the midrib towards the margin at various angles; in the former they are branchless, the principal veins being connected by nearly simple secondary veins; in the latter they are much branched, ramifying in many directions, and giving the surface of the leaf a netted appearance.

Such are the very obvious distinctions of the two great classes of Phanerogamous, or flowering plants; and so far is it from there being any necessity for dissecting a seed in order to ascertain its structure, that this point is one of the most easy determination, and about which there cannot be in one case in five hundred the slightest cause of doubt or difficulty. It is almost impossible to take even a morsel of a plant in the hand without instantly being in possession of the knowledge of the structure of its seed, with respect to the cotyledons.

Thus far have we advanced without a single oostacle to impede us. In all farther investigation no greater degree of knowledge or application is requisite, than what ought to be possessed by every one who would be able to ascertain the genus of a plant. Many of the orders do not depend upon the minute characters of the seed so much as is believed; the structure of the ovarium and position of the ovula are aids which frequently make amends for the absence of fruit: and the nature of the foliage and inflorescence are guides which, though sometimes treacherous, are often as faithful as the fructification itself. But as it is not intended to give the characters of the orders in this place, neither is it necessary to advance farther in an explanation of the manner of determining them; upon that point each order would require a particular note. It may however be confidently believed that

12.

v, Transverse section of a dicotyledonous stem. y, An embryo with many cotyledons.

w, An embryo with two cotyledons.

%, An embryo with four cotyledons.

there are no greater impediments in the road to an acquaintance with the natural relations of plants than those which have been already removed; and that, although neither the science of botany, nor any other science, is to be taken by storm, yet the fortress is sure to be reduced by silent and patient approach.

It only remains to explain briefly the principles upon which the names of the orders, sub-orders, &c., are formed. It is usual, in the school of Jussieu, to give to a natural order a name derived from that of the genus which is understood to be the type of the order, as Ranunculàceæ from Ranúnculus, Rosaceæ from Ròsa, and so on: but several deviations from this principle were admitted by Jussieu, in favour of certain groups of plants, long known by other popular names derived from certain peculiarities; such as Labiàtæ, because their corollas are labiate; Compósitæ, because their flowers are what is commonly called compound; Guttíferæ, on account of the resinous juice in which they abound; and some others. It would, perhaps, have been better if uniformity in nomenclature had not thus been sacrificed to a dread of innovation; but it is now too late to remedy the evil, if such it is; nor would the advantage of alteration be at this day equivalent to the inconvenience. For the purpose of making it at once apparent whether, in speaking of a group of plants, reference is had to an order or a sub-order, it has of late years been thought convenient to terminate the name of the natural order in acea, and that of the sub-order in ea: thus, in speaking of the whole mass of which Ranúnculus is the representative, the word Ranunculaceae is used; but in speaking of the particular division or sub-order of which Ranúnculus forms a part, the term Ranuncùleæ is employed. This manner of speaking is, however, at present very partial in its application; and is of little importance, except in a few cases of which Ranunculaceae is one of the most striking examples. In those orders, the titles of which, necessarily from their grammatical construction, end in ea, as Orchideæ, it is obviously inapplicable, without a total change in a great part of the nomenclature of natural orders, a measure which cannot be too much deprecated.

It may, perhaps, be expected that these remarks should conclude with a recommendation of some work, from which those who are anxious to become fully acquainted with the principles and distinguishing characters of the natural system of botany, may derive the necessary information. Unfortunately, however, such a work has at present no existence. M. Decandolle's Théorie Elémentaire de la Botanique explains the principles upon which the orders of plants are constituted, and M. de Jussieu's Genera Plantarum contains their characters

as determined in 1789: but the latter is now too obsolete to be very useful to the tyro. In our own language the only work that can be consulted upon the subject with advantage is the Flòra Scótica of Professor Hooker, in which the characters of the natural orders of Scottish plants are concisely indicated by Mr. Lindley.

[The foregoing forms a part of the introduction to our Encyclopædia of Plants, Part II., Natural System. In our next Number we shall proceed to give a general view of the divisions and subdivisions of vegetables according to this system, in doing which we shall give figures of all the principal genera, and more especially of those species which are of most usual occurrence in Britain, in order to render this superior mode of studying botany as easily and universally understood as possible.]

(To be continued.)

ART. VIII.__The principal Forest Trees of Europe, considered as Elements of Landscape. By J. G. STRUTT.

THERE is no defect so common in painted or engraved landscapes, as the want of distinctive character in the representations of trees. With the exception of Constable, Nasmyth, Robson, Strutt, and a few others, most artists appear to content themselves with producing variations of a few general and vague forms of masses of foliage, trunks, branches, and spray: it seems to be enough for them to produce a tree, without attempting to represent any particular species; or considering that to give a true idea of nature, the spectator ought to be able to distinguish the sort of tree in the picture, with the same facility with which he distinguishes it in the reality. Why trees should not be represented with the same truth and fidelity as animals, buildings, or other objects, there can be no good reason assigned; and the only way of accounting for it is, by the general residence of landscape painters in cities, and the very little attention paid by most of them to natural history as a science. Were this study to enter into the education of the landscape painter, as much as that of general history enters into that of the historical painter, we should not so frequently have to regret, in the works of our first artists, not only violations of truth and nature in the kinds of trees, but in their situations in regard to soil, surface, water, and other trees or plants. A little knowledge of botany would prevent artists from putting spring and autumnal plants in flower or fruit in

the same picture, placing the plants of woods and shady places in open sunshine, and committing a number of similar violations of nature. The combined knowledge of indigenous zoology, geology, and botany, ought to be considered as essential to the landscape painter as it is to the cultivator. It is one object of our Magazine to direct public attention to this subject; and we are happy in having procured the assistance of Mr. Strutt for the tree department. Every reader, who is acquainted with the admirable engravings in this gentleman's Sylva Britannica and Delicia Sylvarum, will know what to expect from so eminent an artist.

The botanical characters of the trees, which will follow Mr. Strutt's pictorial descriptions, will be given chiefly for the sake of beginners in botany; and to show to artists, selfpractising amateurs, as well as professional men, the detailed forms of the leaves, flowers, and smaller parts. To insure the accuracy of these botanical details, they will be looked over by Mr. George Don, too well known as a scientific botanist to require any eulogium here. - Cond.

IT is a beautiful notion of St. Pierre's, and one which has the advantage of being safe from any positive contradiction, that the earth, on its first assumption of form and laws, appeared clothed, with respect to the vegetable creation, not only