INTRODUCTION. XI 



turbinate, when shaped like a top. 



conical, when tapering upwards ; obconical, when tapering downwards, if in both 

 cases a transverse section shows a circle. 



pyramidal, when tapering upwards ; obpyramidal, when tapering downwards, if 

 in both cases a transverse section shows a triangle or polygon. 



fusiform, or spindle-shaped, when tapering at both ends ; cylindrical, when not 

 tapering at either end, if in both cases the transverse section shows a circle, or some- 

 times 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 ; obcompressed (in the achenes of Compo- 

 sitce), when flattened from front to back. 



articulate or 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 of joint 

 is, in common language, given both to the articulation and the article, but more espe- 

 cially to the former. Some modern botanists, however, propose to restrict it to the 

 article, giving the name of joining to the articulation. 



didymous, when slightly 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 Leaves 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 applied botanically to the consistence of solids are those 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 (Squama) 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 rigour of winter. In the 

 latter case they are usually short, broad, close together, and more or less imbricated, 

 that is, overlapping each other like 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 all 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-like 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 differ- 

 ent from the stem-leaves in size, shape, colour, or arrangement. They are generally 

 much smaller and more sessile. They often partake of the colour of the flower, 



