OUTLINES OF BOTANY. XV11 



simple and entire, when the blade consists of a single piece, with the mar- 

 gin nowhere indented, simple being used in opposition to compound, entire in 

 opposition to dentate, lobed, or divided. 



ciliate, when bordered with thick hairs or fine hair-like teeth. 



dentate or toothed, when the margin is only cut a little way in, into what 

 have been compared to teeth. Such leaves are serrate, when the teeth are re- 

 gular and pointed like the teeth of a saw ; crenate, when regular and blunt or 

 rounded (compared to the battlements of a tower) ; serrulate, and crenulate, 

 when the serratures or crenatures are small ; sinuate, when the teeth are broad, 

 not deep, and irregular (compared to bays of the coast) ; toavy or undulate, 

 when the edges are not flat, but bent up and down (compared to the waves of 

 the sea). 



lobed or cleft, when more deeply indented or divided, but so that the 

 incisions do not reach the midrib or petiole. The portions thus divided take 

 the name of lobes. When the lobes are narrow and very irregular, the leaves 

 are said to be laciniate. The spaces between the teeth or lobes are called 

 sinuses. 



divided or dissected, when the incisions reach the midrib, or petiole, but 

 the parts so divided off, called segments, do not separate from the petiole, even 

 when the leaf falls, without tearing. 



compound, when divided to the midrib or petiole, and the parts so divided 

 off, called leaflets, separate, at least at the fall of the leaf, from the petiole, as 

 the whole leaf does from the stem, without tearing. The common stalk upon 

 which the leaflets are inserted is called the common petiole or the rhachis ; the 

 separate stalk of each leaflet is a petiolule. 



40. Leaves are more or less marked by veins, which, starting from the stalk, 

 diverge or branch as the blade widens, and spread all over it more or less 

 visibly. The principal ones, when prominent, are often called ribs or nerves, 

 the smaller branches only then retaining the name of veins, or the latter are 

 termed veinlets. The smaller veins are often connected together like the meshes 

 of a net, they are then said to anastomose, and the leaf is said to be reticulate or 

 net-veined. When one principal vein runs direct from the stalk towards the 

 summit of the leaf, it is called the midrib. When several start from the stalk, 

 diverge slightly without branching, and converge again towards the summit, 

 they are said to be parallel, although not mathematically so. When 3 or 5 or 

 more ribs or nerves diverge from the base, the leaf is said to be 3-nerved, 5- 

 nerved, etc., but if the lateral ones diverge from the midrib a little above the 

 base, the leaf is triplinerved, quintuplinerved, etc. The arrangement of the 

 veins of a leaf is called their venation. 



41. The Leaflets, Segments, Eiobes, or Veins of leaves are 



pinnate (feathered), wmen there are several succeeding each other on each 

 side of the midrib or petiole, compared to the branches of a feather. A pinnately 

 lobed or divided leaf is called lyrate when the terminal lobe or segment is 

 much larger and broader than the lateral ones, compared, by a stretch of 

 imagination, to a lyre ; runcinate, when the lateral lobes are curved backwards 

 towards the base of the leaf ; pectinate, when the lateral lobes are numerous, 

 narrow, and regular, like the teeth of a comb. 



palmate or digitate, when several diverge from the same point, compared 

 to the fingers of the hand. 



ternate, when three only start from the same point, in which case the dis- 

 tinction between the palmate and pinnate arrangement often ceases, or can only 

 be determined by analogy with allied plants. A leaf with ternate lobes is called 

 trifid. A leaf with three leaflets is sometimes improperly called a ternate leaf: 

 it is the leaflets that are ternate ; the whole leaf is trifoliolate. Ternate leaves 

 are leaves growing three together. 



pedate, when the division is at first ternate, but the two outer branches 



b 



