64. =Cladophylla=, meaning _branch-leaves_. The foliage of Ruscus (the
Butcher's Broom of Europe) and of Myrsiphyllum of South Africa
(cultivated for decoration under the false name of Smilax) is peculiar
and puzzling. If these blades (Fig. 167, 168) are really leaves, they
are most anomalous in occupying the axil of another leaf, reduced to a
little scale. Yet they have an upper and lower face, as leaves should,
although they soon twist, so as to stand more or less edgewise. If they
are branches which have assumed exactly the form and office of leaves,
they are equally extraordinary in not making any further development.
But in Ruscus, flowers are borne on one face, in the axil of a little
scale: and this would seem to settle that they are branches. In
Asparagus just the same things as to position are thread-shaped and
branch-like.

Sec. 2. LEAVES OF SPECIAL CONFORMATION AND USE.

[Illustration: Fig. 169. A young Agave Americana, or Century-plant;
fleshy-leaved.]

165. =Leaves for Storage.= A leaf may at the same time serve both
ordinary and special uses. Thus in those leaves of Lilies, such as the
common White Lily, which spring from the bulb, the upper and green part
serves for foliage and elaborates nourishment, while the thickened
portion or bud-scale beneath serves for the storage of this nourishment.
The thread-shaped leaf of the Onion fulfils the same office, and the
nourishing matter it prepares is deposited in its sheathing base,
forming one of the concentric layers of the onion. When these layers, so
thick and succulent, have given up their store to the growing parts
within, they are left as thin and dry husks. In a Houseleek, an Aloe or
an Agave, the green color of the surface of the fleshy leaf indicates
that it is doing the work of foliage; the deeper-seated white portion
within is the storehouse of the nourishment which the green surface has
elaborated. So, also, the seed-leaves or cotyledons are commonly used
for storage. Some, as in one of the Maples, the Pea, Horse-chestnut,
Oak, etc., are for nothing else. Others, as in Beech and in our common
Beans, give faint indications of service as foliage also, chiefly in
vain. Still others, as in the Pumpkin and Flax, having served for
storage, develop into the first efficient foliage. Compare 11, 22-30,
and the accompanying figures.

[Illustration: Fig. 170. Series of bud-scales and foliage-leaves from a
developing bud of the Low Sweet Buckeye (AEsculus