BOTANY. 



583 



projections shaped like the canine teeth of animals, 

 fig. 6. 



Doubly-dentate is when the teeth are each indented 

 and all pointing upwards, fig. 7. 



Serrated. That is when the margin is cut like a 

 saw, fig. 8. When the projections are small and fine, 

 the margin is said to be serrulate. 



Crenate is when the projections are blunt and point 

 neither upwards or downwards, fig. 9. The margin 

 so described may be either obtusely crenate, acutely 

 crenate, or doubly crenate. 



Armed. This is said of leaves whose margins are 

 defended with prickles as the common holly, the pine 

 apple, and many other plants, fig. lii. 



Ciliated, from cilium, an eye-lash. This term ap- 

 plies to the margin of the leaf, and means that it is 

 fringed with hairs, fig. 10, example Protea ciliatum. 



Rnncinate. Leaves are called runcinate when the 

 margin is cut into deep gashes like the teeth of a pit 

 saw, the points of the teeth pointing backwards, ex- 

 emplified in the commou dandelion, fig. II. 



TERMS DESCRIPTIVE OF THE SURFACE. 



Wrinkled. The leaves of sage, and all others simi- 

 lar, are said to be rugose or wrinkled, caused by the 

 web of the leaf between the veins being more dilated 

 than the veins themselves. 



Blistered. Having a surface like the preceding 

 only extremely so. 



Lacunosum. That is, pitted on the upper surface, 

 caused by the depression of the web of the leat 

 between the more rigid veins. 



Punctated. The surface covered with dots, usually 

 " arising from glands imbedded in the surface of the 

 leaf." 



Coloured. Leaves are said to be coloured when 

 they are of any other colour but green. 



Ribbed. A leaf is said to be ribbed when the 

 divisions of the mid-rib or costa run in direct and 

 parallel lines from the centre to the margin. 



Nerved. When the nerves run in Hues from the 

 base to the point. 



Veined. W T hen the divisions of the costa are nu- 

 merous, and form a net-work over the web of the leaf. 



Armed. When the disk is partially covered with 

 prickles, as the thistle, rose, and some varieties of holly. 



OF THE SITUATION OF LEAVES. 



If a leaf be seated upon, and clings closely to the 

 stem, it is said to be adpressed. If leaves rise from 

 the stem one above another on opposite or on nearly 

 opposite sides, they are described as alternate. If 

 their bases surround the stem, they are said to be 

 amplcxicaide. If so thickly placed as to hide the stem 

 they are said to be conferted. If two opposite leaves 

 are united by their bases, so that the stem appears to 

 run through them, they are said to be connate, that is 

 growing together. If the leaves of water plants grow 

 under the surface, they are described as submersed; if 

 above the surface, they are emerged; and if they float 

 they are said to be natant. 



COMPOUND LEAVES. 



Some of these have been already described, and 

 two of them (the palmate and digitate 1 ) have been 

 already figured ; we now proceed to name and give 

 figures of those of most common occurrence. 



A compound leaf differs from a simple one in this, 

 that whereas the latter stands singly on the petal or 

 footstalk, the former stand in pairs, threes, &c. 



If two leaflets are borne on the footstalk, they are 

 said to be binatc; fig. 1. If the petiole divide at the 



summit, and each division end in two leaflets, it is 

 called bigcviinatc, or a twice-twinned leaf, fig. 2. If 

 one petiole bears three leaflets attached to the end, it 

 is called a tcrnate leaf, example the wood-sorrel, or 

 shamrock, fig. :3. If the petiole be divided, and on 

 the end of each division three leaflets be attached, 

 this disposition is called biternatc, fig. 4. Suppose 



again that the petiole has three branches, each bearing 

 three times three leaflets, then we have a triternatc 

 compound leaf, fig. 5. 



When a petiole is undivided, but bears on each 

 side any number of leaflets, either placed alternately 



