FORMS OF SIMPLE LEAVES. 



75 



on each side of a leaf, so as to make it resemble a violin, as in Rumex 

 pulcher (fig. 140), it is called panduriform (^roe,v^w^x, fiddle). 



148. The same kind of divisions taking place in a simple leaf 

 with radiating venation, gives origin to the terms lobed or cleft 

 (figs. 174, 146), when the divisions extend about half-way through 

 the leaves : and thus they may be three-lobed, five-lobed, seven- 

 lobed, many-lobed; or, trifid, quinquefid, septemfid, multifid, according 

 to the number of divisions. The name of palmate, or palmatifid 

 (fig. 144), is applied to leaves with radiating venation, in which 

 there are several fissures united by a broad expansion of parenchyma, 

 like the palm of the hand, as in Passion-flower and Rheum palma- 

 tum ; while digitate (digitus, a finger), or digitipartite, includes leaves 

 in which there are deeper partitions, five in number, like the fingers, 

 as in Janipha ; and dissected applies to leaves with radiating venation, 

 having numerous narrow divisions, as in Geranium dissectum. When 

 in a radiating leaf there are three primary partitions and two lateral 

 ones spreading and forming divisions on their inner margin only, as 

 in Helleborus (fig. 170), the leaf is called ^jeJate or pedatifid (pes, a 

 foot), from a fancied resemblance to the claw of a bird. 



149. In all the instances already alluded to, the leaves have been 

 considered as flat expansions in which the ribs or veins spread out on 

 the same planes with the stalk. In some cases, however, the veins 

 spread at right angles to the stalk. If they do so equally on all sides, 

 and are united by parenchyma, so that the stalk occupies the centre 

 (fig. 145), the leaf becomes orbicular (orbis, a circle), as in Hydrocotyle; 

 if unequally, so that the stalk is not in the centre, the leaf is peltate 

 (pelta, a buckler), as in the 



Castor oil plant (fig. 146). 

 The edges or margins of or- 

 bicular and peltate leaves 

 are often variously divided. 



150. It is impossible to 

 notice all the forms of 

 leaves without exceeding 

 due limits. The following 

 are enumerated as the 

 most important. When 

 the veins do not spread 

 out, but run from the base 

 to the apex with a narrow 



strip of parenchyma, the leaf is linear or acicular (fig. 147), as in 



Fig. 145. Orbicular leaf of Hydrocotyle vulgaris. Radiating venation, p, Petiole. /, La- 

 mina. 



Fig. 146. Peltate leaf of Ricinus communis, or Castor oil plant. Radiating venation, p, Petiole 

 or leaf-stalk. I, Lamina or blade. 



Fig. 147. Linear, or acicular leaf of Fir. 



(I 



140 



147 



