3 68 



LEAF 



it were a 1., and the common stalk is called the rachis. If the leaflets 

 spring from the sides of the rachis, as in the pea, the 1. is pinnate 

 (F), if all from one point palmate (E). If the leaflets of a pinnate 1., 

 as in many Acacias, are again pinnately cpd., the 1. is bif innate. 

 A 1. with 3 leaflets (as in clover) is ternate or tri -foliolate, with 3 ternate 

 leaflets bitemate. Pinnate 1. may be equally (part-} pinnate (with an 

 even number of leaflets), unequally (impart-} pinnate (with an odd 

 leaflet at the end), or interruptedly pinnate (large and small leaflets 

 alt. as in many Rosaceae). A palmate 1. with 5 or 7 leaflets is often 

 called digitate. The leaflet may have stipule-like organs, or stipels 

 (adjective stipellate). 



The leaf may be dorsiventral, isobilateral, or centric, or replaced 

 by a phyllode, scale, pitcher, or other organ. 



The shape of the leaf-blade or leaflet itself, if simple, or the out- 

 line of a cpd. 1. , may be needle-shaped or acicular as in Pinus, subulate 

 or awl-shaped, tubular as in onion, linear (long and narrow as in 

 Grasses), lanceolate (about 3 times as long as broad, tapering gradually 

 towards the tip ; A in fig.), ovate (about twice as long as broad, and 

 tapering towards the tip; B), cordate (similar, but heart-shaped at 

 the base; C), elliptical (tapering equally to base and tip, and some- 

 what narrow), oval (do. but wider), oblong (sides || for some distance, the 

 ends tapering rapidly; F), reniform (kidney-shaped), orbicular (cir- 

 cular in outline ; if the petiole is inserted at the middle of the blade, 

 as in Tropaeolum, this leaf is termed peltate}, hastate (with two pointed 



jWl 1 ' u -Al 

 v a / AUM-C ;.ag e 



a. 



FORMS OF LEAVES. A, subsessile, exstip., lanceolate with cuneate 

 base, entire, acute. B, sessile, exstip., ovate, serrate below, entire 

 above, acum. C, petiolate, exstip., cordate, crenate, obtuse. D, ses- 

 sile, exstip., somewhat obovate, pinnatifid sinuate, obtuse. E, petio- 

 late, exstip., palmate (digitate), with obtuse oblanceolate leaflets. 

 F, impari-pinnate with triangular adnate slips.; leaflets shortly stalked, 

 oblong, apiculate, the laterals oblique. G, a, plicate 1. in section, 

 b, mucronate apex, c, dentate spiny margin, d, retuse apex, e, glandu- 

 lar hair. 



