To
redden [ Transitive and
intransitive verb ] (past
and past participle reddened, present
participle reddening, 3rd person
present reddens)
Reddening:
The act or
condition (visible to the naked eye) of becoming red coloured of a
plant tissue or organ.
To redden:
To turn or
make red, redder or somewhat red; to give a red colour to. To grow
or become red; to blush.
Reddening of leaves in Autumn.
In botany a reddening is any
changing into red from the original colour of leaves, flowers,
stems, fruits or other plants parts either due to environmental
or internal factors.
Reddening is both a natural phenomenon (as the reddening of
foliage in autumn and winter, the reddening of fruit at ripening
or the reddening of some organs at senescence) or it may be the
symptom of a plant disorder.
For example reddening (symptom) may
be the consequence of:
Weather: e.g. Excessive sun exposure, overheating,
cold weather and frost, water stress.
Diseases: e.g. Phytoplasm, bacteria or virus
infection, as the reddening of tissues at the margin of an
infection.
Parasites: e.g Some insect (as aphids) attack
plants and inject a toxic salivary secretion that causes
cells, leading to a yellowing or reddening discoloration
around the feeding site;
Lack of nutrients: E.g: whith
Magnesium deficiency leaves may redden whereas potassium
deficiency my be signalled by a not corrected reddening of the
leaves late in the autumn.
Chemical attack: Sensitivity to herbicide, or other
toxic compound
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
