FORMS OF LEAVES. 173 
more or less pointed at the apex, so that it somewhat resembles 
in shape the heart in a pack of cards, the leaf is cordate or 
heart-shaped (fig. 343), as in the Black Bryony (Tamus com- 
munis) ; or if of the same shape, but with the apex broader 
than the base, and hollowed out into two rounded lobes, it is 
obcordate or inversely heart-shaped (fig. 350). When a leaf 
resembles a cordate one generally in shape, but with its apex 
rounded, and the. whole blade usually, shorter and broader 
(fig. 349), it is reniform or kidney-shaped, as in the Asarabacca 
(Asarum europeum); 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. 351), it is luwnate or 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 resembles the head of an arrow (jig. 352), the leaf is 
sagittate or arrow-shaped, as in the Arrowhead (Sagittaria 
sagittifoiia) ; when the lobes of such a leaf are placed horizon- 
tally, instead of passing downwards, it is hastate or halbert- 
shaped (fig. 353), as in Sheep’s Sorrel (Rumex <Acetosella) ; or 
when the lobes are entirely separated from the blade, as in the 
upper leaves of the Woody Nightshade (Solanum Dulcamara), 
it is awriculate or hastate-auricled (fig. 354). When the blade is 
perfectly round, the leaf is orbicwlar (fig. 356), a figure which 
is scarcely or ever found ; but when it approaches to orbicular, 
as in Pyrola rotundifolia, the leaf is subrotund or rounded 
(fig. 359). Ben. 
It frequently happens, that a leaf does not distinctly present 
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. 
In many cases we find leaves of different figures on the same 
plant ; under which circumstance the plant is said to be hetero- 
phyllous. Thus, in the Hairbell (Campanula rotundifolia), the 
radical leaves are cordate or reniform, and the cauline leaves 
linear; and this difference of outline between the radical and 
stem leaves is by no means uncommon. In water plants, again, 
where some of the leaves are submersed, while others float 
on the water, or rise above it into the air, as in the Water 
Crowfoot (Ranunculus aquatilis), and Arrowhead (Sagittaria 
sagittifolia), the leaves thus differently situated frequently vary 
in shape. 
5. Form.—By this term we understand the solid configuration 
of the lamina, that is, including its length, breadth, and thick- 
ness. The terms used in defining the various forms are there- 
fore especially applicable to thick or succulent leaves—namely, 
those which are produced when the veins are connected by a 
large development of parenchyma. Such leaves either assume 
