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Show 368 PHYSIOGNOMY OF PLANTS. method which, whilst it continually aims at generality of conception, seeks, at the same time, to penetrate the specialties of phenomena by the consideration of particular instances. The enumeration of forms according to physiognomic diversity is, from the nature of the case, not susceptible of any strict classification. Here, as everywhere else, in the consideration of external conformation, there are certain leading forms which present the most striking contrasts : such are the groups of arborescent grasses, plants of the aloe form, the different species of cactus, palms, needle-trees, Mimosacere, and Musacere. Even a few scattered individuals of these groups are sufficient to determine the character ofa district, and to produce on anon-scientific but sensitive beholder a permanent impression. Other forms, though perhaps much more numerous and preponderating in mass, may not be calculated-either by the outline and arrangement of the foliage, or by the relation of the stem to the branches, by luxuriant vigor of vegetation, by cheerful grace; or, on the other hand, by cheerless contraction of the appendicular organs-to produce any such characteristic impressions. As, therefore, a "physiognomic classification," or a division into groups from external aspect or "facies," does not admit of being applied to the whole vegetable kingdom, so also, in such a classification, the grounds on which the division is made are quite different from those on which our systems of natural families and of plants (including the whole of the vegetable kingdom) have been so happily established. Physiognomic classification grounds her divisions and the choice of her types on whatever possesses "mass" -such as shape, position, and arrangement of leaves, their size, and the character and surfaces (shining or dull) of the parenchyma; therefore, on all that are called more especially the "organs of vegetation," i. e. those on which the preservation-the nourishment and development- of the individual depend: while systematic Botany, on the other hand, grounds the arrangement of natural families on the consideration of the organs of propagation-those on which the continuation or preservation of the species depends. (Kunth, Lehrbuch der Botanik, 1847, th. i. s. 511; Schleiden, die Pflanze und ihr Leben, 1848, s. 100.) It was already taught in the school |