rundo Donax.]

[Illustration: Fig. 11.--Nodes.

1. Glabrous node; 2. bearded node; 3. node cut longitudinally.]

The nodes are in most cases very conspicuous and they are often found
swollen. However, it must be remembered that the enlargement at the node
is not due to the increase in size of the actual node, but due to growth
in thickness of the base of the leaf-sheath. (See fig. 11-3.) Nodes may
be pale or coloured, glabrous, hairy or bearded with long hairs. When
the stem is erect the nodes are short and of uniform size all round.
But, if the stem is bent down or tipped over by accident, the nodes
begin to grow longer on the lower side until a curvature sufficient to
bring the stem to the erect position is formed and then it ceases to
grow.

As already noted some perennial grasses have creeping stems and stolons,
while others may have rhizomes. The grass _Cynodon dactylon_ develops
several underground stolons which are covered with white scale leaves
and whose terminal buds are hard and sharp so that they may be able to
make their way through the soil. The rhizomes when continuous and
elongated are usually sympodia formed by the lower portions of the
aerial shoots. The aerial shoot comes into the air and its lower portion
is continued by a branch arising from a lower leaf axil beneath the
soil.

=The leaf.=--Leaves are two-ranked and alternate, and very often they
become crowded at the lower portions of the shoots so as to form basal
tufts, though they are farther apart in the upper portions of these
shoots. Three distinct kinds of leaves are met with in grasses. First,
we have the fully formed foliage leaves so characteristic of grasses.
These are most conspicuous and are formed in large numbers.

The other two kinds of leaves are neither so conspicuous nor so numerous
as the foliage leaves. At the base of shoots occur abortive leaves which
are really rudimentary sheaths. These are called =scales=. The third
kind of leaf is a modified structure called the =prophyll= or
=prophyllum=. (See fig. 12.) It is the first leaf occurring in every
branch on the side next to the main shoot and it is a two-keeled
membranous structure resembling somewhat the palea found in the
spikelets of grasses. The portion of the prophyll between the keels is
concave due to the pressure of the main stem, while the sides beyond the
keels bend forward clasping the stem.

[Illustration: Fig. 12.--Prophylla.

A. A branch with its prophy