LEAF OR PHYLLOME.—ORGANS OF REPRODUCTION. 15 
c. The Leaf or Phyllome.—The leaf is commonly a more or 
less flattened expansion of the stem or branch (figs. 21 and 22). 
As already stated, the point from which it arises is called a 
node ; and the space between two nodes is therefore termed an 
mternode. In its highest state of development the leaf con- 
sists of three parts ; namely, of an expanded portion, which is 
usually more or less flattened (figs. 21, 1, and 22,1), called the 
lamina or blade ; of a narrower portion, by which the lamina is 
connected with the stem, termed the petivle or leaf-stalk (figs. 
21, p, and 22, p); and of a third portion at its base, which either 
_ exists in the form of a sheath (fig. 21, d) encircling the stem, 
or as two little leaf-like appendages on each side, which are 
called stipules (fig. 22, s,s). These three portions are by no 
Bre, 21. 
2ETS 
Fr 
Fig. 21. Leaf and piece of stem of Polygonum Hydropiper. 1. Lamina or 
blade. p. Petiole. d. Sheath or stipular portion.— /fig, 22. Leaf and 
portion of a branch of Sulix aurita. 7. Branch. 6. Leaf-bud. J. Lamina 
with the upper portion removed, and attached by a petiole, p, to the 
stem, s, s. Caulinary stipules, 
means always present, for it frequently happens that one or two 
of them are absent; and in such cases, when the petiole is 
absent, the leaf is said to be sessile, and if the stipulate portion 
is wanting the leaf is described as exstipulate. When a leaf 
becomes thick and fleshy, instead of presenting its ordinary 
flattened appearance, it is termed succulent. 
2. OrGANS OF ReEpropuction.—As already noticed, the 
parts of a flower are only leaves in a modified condition adapted 
for special purposes ; and hence a flower-bud is analogous to a 
leaf-bud, and the flower itself to a branch the internodes of 
which are but slightly developed, so that all its parts are situated 
in nearly the same plane. 
a. The Flower-stalk or Pedwncle.—The stalk which bears a 
solitary flower, as in the Tulip, or several sessile flowers (jig. 23, 
jt)—that is, flowers without individual stalks—is called the flower 
J 
