46 FIRST LESSONS WITH PLANTS 



(as in Fig. 39, which is a cordate -ovate leaf) ; 

 reniform, or kidney -shaped ; auriculate, or eared; 

 sagittate, or arrow- shaped ; abrupt, or suddenly nar- 

 rowed to the petiole (as in the broader leaves in 

 Fig. 37); gradually narrowed (as in Figs. 36, 38). 

 The cavity or recess in the base of a leaf, like 

 the grape (Figs. 24, 25), or moonseed is a sinus. 

 56. The features of the margins of leaves, 

 like their forms, are interesting because they are 

 intimately related to the origin or evolution of the 

 particular leaf (and, therefore, of the plant), and 

 also as a means of affording descriptive char- 

 acters. The simple, straight margin is said to be 

 entire (Figs. 26, 29, 30, 36, 37). Departures from 

 this form are the serrate, or saw -toothed (Fig. 35) ; 

 dentate, or toothed (Figs. 23, 24, 25, 38, the last 

 being, perhaps, intermediate between serrate and 

 dentate) ; crenate, or scalloped (Fig. 39) ; repand, 

 or wavy, or undulate (Fig. 30 is obscurely so) ; 

 sinuate, which is a deep undulation ; and then 

 follow the deep margins, as cut, jagged, lobed. 

 cleft, and the like. Leaves are said to be cleft 

 when the divisions extend deeper than the middle 

 of the blade, and lobed when they are not more 

 than half the depth of the blade. 



56a. The diagrams of forms and margins of leaves given by 

 Linnaeus are reproduced in exact form and size in Fig. 40: 1, 

 orbiculate ; 2, sub-orbiculate (or subrotundate) ; 3, ovate ; 4, oval, 

 or elliptical ; 5, oblong ; 6, lanceolate [narrower than present bot- 



