In botany a scale or
squama is a small, thin, usually dry,
often appressed plant structure,
such as any of the protective leaves
that cover a bud or the
bract that
subtends a
flower in a sedge or a thin flake,
an exfoliation of dead epidermis
shed from the surface of the
epidermis.
Scales
or scale leaves are also the
fleshy leaves of a bulb.
The body of the bulb is made up of
concentric layers of fleshy scales which are
modified leaves. The scales
are food and
waterstorage organ that overlap
and cover the bud.
A
scale or peltate hair is a common type of
trichome a plate or shield-shaped
cluster of cells attached directly to the
surface or borne on a
stalk of some kind.
Scale is a diseased
condition of plants caused by
scale
insects that attaches to plants and sucks plant fluids for nutrition. It
coats itself with a covering (hence scale) that makes it quite resistant
to pesticides, which are only effective against them when they are in
the juvenile crawler stage. Scale, however can be controlled with
horticultural oil, which suffocates them, or through biological
controls.
Some species of climbing
plants develop holdfast roots which help to support the vines on
trees, walls, and rocks. By forcing their way into minute pores and
crevices, they hold the plant firmly in place.
Climbing plants, like the poison ivy (Toxicodendron
radicans), Boston ivy (Parthenocissus
tricuspidata), and trumpet creeper (Campsis
radicans), develop holdfast roots which help to
support the vines on trees, walls, and rocks. By forcing their
way into minute pores and crevices, they hold the plant firmly
in place. Usually the Holdfast roots die at the end of the first
season, but in some species they are perennial. In the tropics
some of the large climbing plants have hold-fast roots by which
they attach themselves, and long, cord-like roots that extend
downward through the air and may lengthen and branch for several
years until they strike the soil and become absorbent roots.
Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House,
1994
A
scale or Scale-like leaves is a small sharp-pointed
A
bud scale is a kind of specialized 
Scales
or scale leaves are also the 
A
scale or peltate hair is a common type of
