Answer:
Placenta is a
flattened, cushion like tissue on which one or more ovules are attached.
The various types of
placenta ion seen in the flowers are described in the following table
Type of
Placentation
Description with
example
Diagram
Marginal
There is a single placenta
which develop along the junction of two fused margins, e.g., pea.
Axile
Mutlicarpellary, syncarpous
gynoecium inward growth of carpel's margin forms a multicarpellary condition
that contains an axis in the centre.
Placenta arises from central
axis bearing ovules. e. g., Solanum, China rose.
Parietal
The number of placenta
corresponds to number of fusing carpels. Sometimes the ovules bearing
placenta grow inward to form false septa and thus ovary becomes bilocular(e.g.,
mustard) and trilocular e.g., Cucurbit
Free central
The ovary is unilocular and
ovules are borne on the central-axis and not connected to the ovary wall by
septum, e.g., Dianthus, Silensa.
Basal
The ovary is unilocular and
the single ovule is borne at the base of the ovary attached by a single
placenta, e.g., sunflower, wheat.
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