LEAVES. 61 
apex, or diverge gradually from the midrib, are Tittle 
mified, placed parallel to each other, and connected by 
pie transverse veins. See Frontispiece, Fig. 3, the leaf 
Lady’s Slipper, one of the Orchidee. The leaves of the 
asses and rushes, illustrate this structure. 
206. In Coniferz and in Cycadeae, trees of an exogenous 
structure, the leaf resembles that of endogenous plants i in 
the arrangement of its veins. 
Leaves are either simple or compound. 
207. Ina simple leaf (Fig. 9, p. 59), the petiole is undi- 
vided, and the lamina or disc consists of a single piece. The 
simple leaf, when divided deeply, somewhat resembles the 
compound leaf: in the simple leaf, however, each division is 
continuous in its leafy part with the leafy parts of the divi- 
sions on each side, so that we cannot completely separate 
one division without tearing more or less those between 
which it is situated; as in the common hawthorn, which ° 
ht at first be considered a compound leaf, from its nu- 
s and deep divisions, but which is truly a simple leaf. 
208. A compound leaf (compositum), consists of several 
leaves or leaflets (foliola) attached to a common petiole 
rachis), and quite distinct from each other in every part, so 
that one may be detached without injuring any of the 
others. See Fig. 10. page 65. 
209. Buds are not found in the axille of the leaflets of 
compound leaves. In them, they occur only at the base of _ 
the common petiole ; and the whole is considered as only one _ 
a 
_ 210. The branches of the petiole or petiolets of the leaflets 
are called petiolets, or secondary petioles. Sometimes the pe- _ 
eee ee tention es, or branches of the Se 
le s, the leaf is called supra decompound. : a 
211. sonnet inn iy <a esata Fe 
iolet, or rather the leaflet, is compound, in which case the ae 
whole leaf is called decompound. And when the leaflets arise 
