48 
LEAVES. 
divisions extend to the midrib or petiole ; this has the appear- 
ance of a branch with separate leaves attached to it. The 
whole is considered as one leaf, because in its earliest state it 
arises from the axis of a single piece ; and its subsequent di- 
visions in the form of leaflets, are all in one plane. 
a. Pinnate (from pinna^ a wing) : Fig. 47, a, represents the petiole, or principal 
leaf-stalk, bearing leaflets arranged opposite to each other ; these may be either 
petioled or sessile ; b h represent the stipules ; the whole taken together forms 
Fig. 47. 
one compound pinnate leaf. Binate ; when two leaflets only spring from the 
petiole, as in Fig. 4*7,0. Ternate ; when three leaflets arise from the petiole, as 
Fig. 48, a. Biternate is a second division of tlirees, as Fig. 48, h. Triternate is a 
third division of threes, as Fig. 48, c. Decompound, 
when a pinnate leaf is again divided, or has its 
.eaves twice compound, as Fig. 49, a. At 6 is a 
representation of tricompound leaves. 
56. Various appearances of Leaves. 
—Compound leaves are confined to 
Exogenous plants, and are reticulated, Fig. 
or net-veined. Parallel-veined leaves, 
though divided, are never jointed ; 
therefore, in Endogenous plants, there are no compound leaves. 
Fig. 50, at a, is a leaf of the Ilex aquifolium (holly) ; it is oval and dentate, with 
tmneseent teeth. 
6 is a leaf of the Malva-c,rispa (mallows) ; it is seven-lohed, crisped, or urregularly 
piatted, and finely crenulate ; venation, radiate. 
c is a leaf of the Hydroeotyle trideritata ; it is cuneiform, dentate at the summit 
<? is a leaf of the Corchorus japonicus ; it is oval-acuminate, doubly denticulate 
Fig. 50. 
Fig. 51, a, is & jlahelliform or fan-shaped leaf, two-lobed, and crenulate. 
b is oval-acuminate, Jive-ribbed, ribs converging. 
c is sub-cordate, oval-acuminate, undulate. 
I. Pinnate— Binate— Ternate— Biternate— Triternate— Decompound.— 56. No compovnd leaves W 
\ Oogenous i»lants. — Explain figures 49, 50. 
