Everything about Petal totally explained
A
petal (from
Ancient Greek petalon "leaf", "thin plate"), regarded as a highly modified leaf, is one member or part of the
corolla of a
flower. The corolla is the name for all of the petals of a flower; the inner
perianth whorl, term used when this isn't the same in appearance (color, shape) as the outermost whorl (the
calyx) and is used to attract
pollinators based on its
bright color. It is the inner part of the
perianth that comprises the sterile parts of a flower and consists of inner and outer
tepals. These tepals are usually differentiated into petals and
sepals. The term "tepal" is usually applied when the petals and sepals are similar in shape and color. In a "typical" flower the petals are showy and colored and surround the reproductive parts. The number of petals in a flower (see
merosity) is indicative of the plant's classification:
eudicots (the largest group of
dicots) having typically four or five petals and
monocots and
magnoliids having three, or some multiple of three, petals.
There exists considerable variation in form of petals among the
flowering plants. The petals can be united towards the base, forming a
floral tube. In some flowers, the entire perianth forms a cup (called a
calyx tube) surrounding the
gynoecium, with the sepals, petals, and stamens attached to the rim of the cup.
The flowers of some species lack or have very much reduced petals. These are often referred to as
apetalous. Examples of flowers with much reduced perianths are found among the
grasses.
The petals are usually the most conspicuous parts of a flower, and the petal whorl or corolla may be either radially or bilaterally symmetrical. If all of the petals are essentially identical in size and shape, the flower is said to be
regular or
actinomorphic (meaning 'ray-formed'). Many flowers are symmetrical in only one plane (for example, symmetry is bilateral) and are termed
irregular or
zygomorphic (meaning yoke- or pair-formed). In
irregular flowers, other floral parts may be modified from the
regular form, but the petals show the greatest deviation from radial symmetry. Examples of zygomorphic flowers may be seen in
orchids and members of the
pea family. The petal is the colorful, often showy part of a plant.
Other structures which may look like petals
Some plants have petaloid
stamens, in plants like
Canna that have true petals and
staminodes, the stamen (staminodes) are modified to look like large showy petals.
A number of plants have
bracts that resemble petals for example in
Bougainvillea and
Cornus florida (flowering dogwood). Petal-like bracts are common features in some plant families like
Euphorbiaceae.
In many plants of the
aster family such as the sunflower,
Helianthus annuus, the circumference of the
flower head is composed of ray florets. Each ray floret is anatomically an individual flower with a single large petal.
Corolla
Corolla is the collective term for
petals of a flower taken as a group within the
calyx. Normally the corolla is the most conspicuous part of a flower and of a bright colour other than green. The concept of corolla description is widely used in
botany as a primary determinant of
vascular plant identification. Alternatively the corolla may be considered as the inner
whorl of the
perianth structure. The role of the corolla in plant
evolution has been studied extensively since
Darwin postulated a theory of the origin of elongated corollae.
Further Information
Get more info on 'Petal'.
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