A flora of Manila - Rainforestation

DEFINITIONS OF TERMS H
onion, Rarlic, etc., and those where the scales are thick and narrow are
called scaly bulbs.
As to the arrangement of branches and leaves, they are opposite when
two are borne at the same node from ppposite sides of the stem; whorled
or verticiUate when three or more are borne at the same node, arranged
regulai-ly around the stem; fascicled or fasciculate when two or more
are borne at the same node on the same side of the stem; alternate when
one is borne at each node on one side, anJ the next above or below on
the opposite side of the stem; distichous when regularly arranged one
above another in two opposite rows; and seotnd when all are turned
toward one side.
THE LEAVES.—A typical complete leaf consists of the blade or lamina,
the broad thin part of ordinary leaves, the petiole or leaf-stalk, and a
pair of stipules, variously shaped appendages at the base of the leaf-stalk
or at the nodes, which may be leaf-like, scale-like, or even represented
by sheaths or by spines. Stipules are frequently wanting, such plants
being then teiTned exstipulate. The end by which the leaf, or any other
part of a plant is attached, is called the base; the opposite or free end,
the apex.
The petiole or leaf-stalk is frequently wanting, the leaves being then
called sessile. When the leaf-base clasps the stem it is called amplexicaul
or stem-clasping ; when the lobes meet around the stem so that the blade
appears as though it were pierced by the stem, it is called perfoliate;
when the edges of the leaf extend downward along the stem as ridges
or wings it is called decurrent; when the base of the blade or the petiole
forms a more or less closed vertical cylinder surrounding the stem, it is
called sheathing.
When the leaves are inserted on a stem or branch, they are termed
cauline; when they or the flowers are borne on the roots or rhizomes or
very close to the base of the stem, they are termed radical. Radical
leaves that spread in a circle on the ground forming a rosette are called
rosulate.
Leaves are composed of a framework, consisting of ribs and veins,
and of the softer tissue. When there is only one main vein much
stronger than the others it is called the midrib; the primary divisions
on each side are called the lateral veins or nerves, and the ultimate
divisions the veinlets, or nervules. In cases where several equally strong
veins radiate from the top of the petiole, they are termed palmately, or
digitately nerved or veined, or in peltate leaves radiatcly nerved. In
palmately nerved leaves, where the veins all start from the base, they
are called 3-nerved, 5-nerved, etc., according to the number of nerves,
but when some start just above the base they are called 3-plinerved,
S-plinei'ved, etc.
Venation is the term applied to the method of arrangement of the
veins; there are two principal kinds, parallel-veined and netted-veined
or reticulate. In parallel-veined leaves the whole frame work consists of
slender ribs or veins that run parallel to each other, either from the
base to the apex, or from the midrib to the margins, not dividing and
subdividing and fonning meshes. In netted-veined or reticulate leaves
the veins branch and rebranch into finer and finer veinlets which unite
with each other to form meshes; this network of veins is usually spoken
of as the reticulations. Sometimes the nerves are so obscured by other