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It is important to recognize that Fruits Developmental is a
board topic. Thus this web quest gives
an introduction. This presentation is organized in terms of the general areas
represented by our research. Fruit development and ripening are unique to
plants and represent an important component of human and animal diets.
A fruit results from maturation of one or more flowers, and the gynecologic
of the flower(s) forms all or part of the fruit. Inside the ovary/ovaries are
one or more ovules
where the megagametophyte contains the mega gamete or egg
cell. After double fertilization, these ovules will
become seeds. The ovules are fertilized in a process that starts with pollination,
which involves the movement of pollen from the stamens to the stigma of
flowers.
After pollination, a tube grows from the pollen through the stigma
into the ovary to the ovule and two sperm are transferred from the pollen to
the megagametophyte. Within the megagametophyte one of the two sperm unites
with the egg, forming a zygote, and the second sperm enters the central cell forming
the endosperm mother cell, which completes the double fertilization process.
Later the zygote will give rise to the embryo of the seed, and the endosperm
mother cell will give rise to endosperm, a nutritive tissue used by the embryo.
As the ovules develop into seeds, the ovary begins to ripen and the ovary wall,
the pericarp, may become fleshy (as in berries or drupes), or form a hard
outer covering (as in nuts). In some multiseeded fruits, the extent to which
the flesh develops is proportional to the number of fertilized ovules. The
pericarp is often differentiated into two or three distinct layers called the exocarp
(outer layer, also called epicarp), mesocarp (middle layer), and endocarp
(inner layer).
In some fruits, especially simple fruits derived from an inferior
ovary, other parts of the flower (such as the floral tube, including
the petals,
sepals,
and stamens),
fuse with the ovary and ripen with it. In other cases, the sepals, petals and/or stamens and style
of the flower
fall off. When such other floral parts are a significant part of the fruit, it
is called an accessory fruit. Since other parts of the
flower may contribute to the structure of the fruit, it is important to study
flower structure to understand how a particular fruit forms.
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