5 2 
THE LEAF 
The leaf may be dorsiventral , isobilateral , or centric , or replaced by 
a phyllode, scale , pitcher , or other organ (see above). 
The shape of the leaf-blade or leaflet itself, if simple, or the outline 
of a compound leaf, may be needle-shaped or acicular as in Pinus, subu- 
late 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 somewhat 
narrow), oval (do. but wider), oblong (sides parallel for some distance, 
the ends tapering rapidly; F), reniform (kidney-shaped), orbicular 
(circular 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 
lobes sticking out horizontally at the base), sagittate (two lobes project- 
ing towards the stem), spattdate (spoon-shaped, as in daisy), &c. If a 
leaf be of lanceolate shape but the gentle tapering be towards the base, 
it is called oblcinceolate (E), and so also leaves may be obovate or obcordate . 
If wedge-shaped, tapering to the base, it is ctineate. The leaf may be 
oblique or asymmetrical (F), when the midrib divides it into unequal 
halves, as in Begonia. 
The leaf (or leaflet) may be entire , i.e. without notches in the 
margin (A), or incised ; the margin may also be fringed or fimbriate , 
Fig. 3. Forms of Leaves. A, subsessile, exstipulate, lanceolate 
with cuneate base, entire, acute. B, sessile, exstipulate, ovate, serrate 
below, entire above, acuminate. C, petioiate, exstipulate, cordate, 
crenate, obtuse. D, sessile, exstipulate, somewhat obovate, pinnatifid 
sinuate, obtuse. E, petioiate, exstipulate, palmate (digitate), with 
obtuse oblanceolate leaflets. F, impari-pinnate with triangular adnate 
stipules; leaflets shortly stalked, oblong, apiculate, the laterals oblique. 
G, a , plicate leaf in cross section, b , mucronate apex, c , dentate spiny 
margin, d , retuse apex, e> a common form of glandular hair. 
