THE LEAF. 13 



kinds of venation of simple leaves you have been studying. 

 Pinnately-lobed leaves pass by slight gradations first into 

 pinnately-sected, and finally into pinnately - compound 

 leaves. And, in the same way, palmately-compound leaves 

 are formed. It requires a good deal of observation to de- 

 cide correctly in all cases between deeply-divided leaves 

 and compound leaves. If the green matter of the blade 

 reaches around the framework as far as the midrib, and 

 is continued along it, however slightly, the leaf is simple ; 

 or if in palmate-veined leaves the green matter is contin- 

 ued about the summit of the petiole, the leaf is divided and 

 not compound. Leaflets are often jointed to the rachis or 

 petiole. Gather all the compound leaves you can find, 

 point out and name their parts, and say whether they are 

 pinnate or palmate. If pinnate, say how many pairs of 

 leaflets they have. 



The leaflets of compound leaves present the same dif- 

 ferences of margin, apex, base, incision, and outline, as the 

 blades of simple leaves, and the same terms are used in 

 describing them. A scientific description of a compound 

 leaf would require that the kind of leaf should be named, 

 and its leaflets described as if they were the blades of sim- 

 ple leaves. 



EXERCISE VI. 

 Varieties of Compound Leaves. 



Pinnately-compound leaves may have their leaflets in 

 one, two, three, or many pairs. They may end with an odd 

 leaflet, as in Fig. 46, when they are said to be unequally 

 pinnate, or like Fig. 47, which is said to be abruptly or 

 equally pinnate. If the rachis end in a tendril (Fig. 48) it 

 is said to be a cirrous leaf. When they resemble Fig. 49, 

 they 'are said to be interruptedly pinnate, and lyrately pin- 

 nate when they resemble Fig. 50. When the leaflets of a 

 pinnate leaf themselves become pinnate, as seen in Fig. 51, 

 the leaf is said to be bipinnate. A further continuation of 



