164 



ORGANOGRAPHY. 



Fig. 337. 



When the leaflets of a pinnate leaf become themselves pinnate, 

 or in other words when the partial petioles which are arranged 

 on the common petiole exhibit the characters of an ordinary- 

 pinnate leaf, it is said to be bipinnate (fig. 335), as in some 

 species of Acacia. The leaflets 

 borne by the partial or secondary 

 petioles are commonly termed pin- 

 nides. When the pinnules of a bi- 

 pinnate leaf become themselves pin- 

 nate, it is tripinnate {fig. 336), as 

 in the Meadow Eue {Thalictrum 

 minus). When the division extends 

 beyond this, the leaf is decompound 

 {fig. 337), as in many Umbelliferous 

 Plants. 



2, Palmately -veioicd Com'pound 

 Leaves. — Such a leaf is formed when 

 the ribs of a palmately- veined leaf 

 bear separate leaflets. These leaves 

 are readily distinguished from those 

 of the pinnate kind, by their leaflets 

 coming off from the same point. 

 We distinguish several kinds ; thus, 

 a leaf is said to be Innate, bifoliate, 

 or unijugate, if it consists of only- 

 two leaflets springing from a com- 

 mon point {fig. 338), as in Zygo- 

 phyllwn ; it is ternate or trifoliate 

 if it consists of three leaflets arranged in a similar manner {figs. 

 324 and 339), as in the genus Trifolium (Trefoil), which receives 

 its name from this circumstance; it is quadrinate or quadri- 



Fig. 337. A decompound Jeaf. 



Fig. 338. 



Fig. 339. 



Fig. 340. 



Fig. 338. A binate leaf. Fig. 339. Ternate or trifoliate leaf.- 



Quadrifoliateleaf of Marsilea quadrifolia. 



-Fig. 340. 



foliate if there are four leaflets {fig. 340), as in Herb Paris 

 {Paris quadrifolia) ; it is quinate or quinquefoliate if there are 



