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xi
INTRODUCTION.

turbinate, when shaped like a top.

conical, when tapering upwards ; obconical, when tapering downwards, if in both cases a transverse section shows a circle.

pt/ramidal, when tapering upwards ; ohpyramidal^ when tapering downwards, if in both cases a transverse section shows a triangle or polygon. fusiform^ or spindle-shaped, wlien tapering at both ends ; cylindrical, when not tapering at either end, if in both cases the transverse section shows a circle, or sometimes irrespective of the transverse shape. terete, when the transverse section is not angular ; trigonous, triquetrous, if the transverse section shows a triangle, irrespective in both cases of longitudinal form. compressed, when more or less flattened laterally ; depressed, when more or less flattened vertically, or at any rate at the top ; ohcompressed (in the achenes of Compodtce), when flattened from front to back. articulate ov jointed, if at any period of their growth (usually when fully formed and approaching their decay, or in the case of fruits when quite ripe) they separate, without tearing, into two or more pieces placed end to end. The joints where they separate are called articulations, each separate piece an article. The name oi joint is, in common language, given both to the articulation and the article, but more especially to the former. Some morlern botanists, however, propose to restrict it to the article, giving the name o^ joining to the articulation.

didymoiis, when sh'ghtly two-lobed, with rounded obtuse lobes. moniliform, or beaded, when much contracted at regular intervals, but not sepa- rating spontaneously into articles.

55. In their consistence laeaves or other organs are fleshy, when thick and soft ; succulent is generally used in the same sense, but implies the presence of more juice. coriaceous, when firm and dry, or very tough, of the consistence of leather. membranous, when thin and not stiff. scarious or scariose, when very thin, more or less transparent and not green, yet rather stiff.

56. The terms apphed botanically to the consistence of solids are thos3 in general use in common language.

57. The mode in which unexpanded leaves are disposed in the leaf-bud is called their vernation or prcefoliation ; it varies considerably, and technical terms have been proposed to express some of its varieties, but it has been hitherto rarely noticed in descriptive botany.


§ 6. Scales, Bracts, and Stipules.

58. Scales (Squamce) are leaves very much reduced in size, usually sessile, seldom green or capable of performing the respiratory functions of leaves. In other words, they are organs resembling leaves in their position on the plant, but differing in size, colour, texture, and functions. They are most frequent on the stock of perennial plants, or at the base of annual branches, especially on the buds of future shoots, when they serve apparently to protect the dormant living germ from the rigovir of winter. In the latter case they are usually short, broad, close together, and more or less imbricated, that is, overlapping each other Hke the tiles of a roof. It is this arrangement as well as their usual shape that has suggested the name of scales, borrowed from the scales of a fish. Imbricated scales, bracts, or leaves, are said to be squarrose, when their tips are pointed and very spreading or recurved.

59. Sometimes, however, most or aU. the leaves of the plant are reduced to small scales, in which case they do not appear to perform any particular function. The name of scales is also given to any small broad scale-Hke appendages or reduced organs, whether in the flower or any other part of the plant.

60. Bracts {Bractece) are the upper leaves of a plant in flower (either all those of the flowering branches, or only one or two immediately under the flower), when different from the stem-leaves in size, shape, 0010^0", or arrangement. They are generally much smaller and more sessile. They often partake of the colour of the flower,