ELEMENTS OF STKUCTUR.VL EOTAKY. 



of the stem, giving rise to what is called the dccarrcni 

 form (Fig. 131). 



The terms by which simijle leaves are described are 

 applicable also to the leaflets of compound leaves, to 

 the sepals and petals of flowers, and, in short, to any 

 flat forms. 



Fig. 132. 



114. We have already explained that comijound 

 leaves are of two forms, jnnnate and palmate. In the 

 former, the leaflets are arranged on each iiide o 

 the midrib. There may be a leaflet at the end, 

 in which case the leaf is odd-piniiate, or the 

 terminal leaflet may be wanting, and then the leaf is 

 nnqAhj pinnate. In the Pea, the 

 ■1 (' is pinnate and terminates in a 

 tendril (Fig. 98). Very frequently 

 the primary divisions of a jiinnate 

 leaf are themselves pinnate, and 

 the whole leaf is then ticicc-pitmate 

 (Fig. 132), If the subdivision is 

 continued through another stage, '^^^ 

 the leaf is t^irice-pinnate, and so on. 

 Somiitimee, as in the leaves of the 

 Tomato, very small leaflets are 

 found between the larger ones, and 

 this form is described as internipt- 

 cdlij2Jinnaic,(Fig. 133). Fig. 133. 



