ORGANS OF NUTEITIOX. 161 



a cordate one generally in shape, but vrith. its apex rounded, 

 and the whole blade usually shorter, and broader (Jig. 323), it 

 is reniform or kidney -shaped, as in the Asarabacca (Asanim 

 europceum) ; when a leaf is reniform but with the lobes at the 

 base of the lamina pointed, so that it resembles the form of a 

 crescent {fig. 325), it is lunate ov crescent-shaped, as in Passiflora 

 lunata. When the blade is broad and hollowed out at its base 

 into two acute lobes, and pointed at the apex, so that it resem- 

 bles the head of an arrow (fig. 326), the leaf is sagittate or arrow- 

 shaped, as in the Arrow-head {Sagittaria sagittifolia): when the 

 lobes of such a leaf are placed horizontally, instead of passing 

 downwards, it is hastate or halbert-shaped {fig. 32"). as in 

 Sheep's Sorrel {Rumex Acetosella) ; or when the lobes of such a 

 leaf are separated from the blade, as in the upper leaves of the 

 "Woody Nightshade {Solatium Dulcamara), it is auricidate {fig. 

 328). When the blade is perfectly round, the leaf is orhicidar 

 {fi'g. 330), a figure which is scarcely or ever found, but when it 

 approaches to orbicular, as in Pyrola rotundifolia, the leaf is 

 suhrotund or rounded {fig. 329). 



It frequently happens, that a leaf does not present accurately 

 any of the above-described figures, but exhibits a combination 

 of two of them, in which case we use such terms as ovate-lance- 

 olate, linear-lanceolate, cordate-ovate, cordate-lanceolate, elliptico- 

 lanceolate, roundish-ovate, &c., the application of which will be 

 at once evident. 



6. Form. — By this term we understand the solid configuration 

 of a leaf, that is including its length, breadth, and thickness. The 

 terms used in defining the various forms are therefore especially 

 applicable to thick, fleshy, or succulent leaves — namely, those 

 which are commonly produced when the veins are connected by 

 a large development of parenchjTua. Such leaves either assume 

 / some regular geometrical figures, as cylindrical, pyramidal, coni- 

 cal, prismatic, &c., or approach to some well-known objects, and 

 are hence termed acicidar or needle-shaped, ensiform or sword- 

 like, acinaciform or scimitar-shaped, dolahriform or axe-shaped, 

 clavate or club-shaped, linguiform or tongue-shaped, &c. The 

 above terms need no further description. In other instances, 

 the leaf, instead of having its veins entirely connected by paren- 

 chyma, is more or less hollowed out in its centre, when it is said 

 to be tubular, hood-shaped, urn-shaped, &c. Various other sin- 

 gular forms are also found, some of which will be hereafter 

 alluded to in speaking of the transformation of leaves. 



Besides the above described modifications of tJae Margin, In- 

 cision, Apex, Outline, and Form of the blades of simple leaves, 

 they also present various modifications with regard to their 

 surface, texture, colour, &c. For an explanation of these we 

 must refer to the contents generally of this manual. 



2. CoJiPouND Leaves. — We have already defined a compound 



