Parietal placentation – Definition & Detailed Explanation – Botanical Glossary

I. What is Parietal Placentation?

Parietal placentation is a type of arrangement of ovules within the ovary of a flower. In this type of placentation, the ovules are attached to the inner wall or the periphery of the ovary. This is in contrast to axile placentation, where the ovules are attached to a central column or axis within the ovary.

Parietal placentation can be further classified into different types based on the number and arrangement of ovules within the ovary. This type of placentation is commonly found in dicotyledonous plants and is associated with superior ovaries.

II. How does Parietal Placentation differ from Axile Placentation?

The main difference between parietal and axile placentation lies in the arrangement of ovules within the ovary. In parietal placentation, the ovules are attached to the inner wall or periphery of the ovary, while in axile placentation, the ovules are attached to a central column or axis within the ovary.

Another difference is that parietal placentation is commonly found in dicotyledonous plants with superior ovaries, while axile placentation is more common in monocotyledonous plants with inferior ovaries.

III. What are the different types of Parietal Placentation?

There are several types of parietal placentation based on the arrangement of ovules within the ovary. Some of the common types include:
– Marginal placentation: where the ovules are attached along the margin or edge of the ovary.
– Axile placentation: where the ovules are attached to a central axis or column within the ovary.
– Free-central placentation: where the ovules are attached to a central column but are not fused with the ovary wall.
– Basal placentation: where the ovules are attached at the base of the ovary.

Each type of parietal placentation has its own unique characteristics and implications for fruit development.

IV. How does Parietal Placentation affect fruit development?

Parietal placentation plays a crucial role in fruit development. The arrangement of ovules within the ovary determines the structure of the fruit and the distribution of seeds within it.

In parietal placentation, the ovules are attached to the inner wall or periphery of the ovary, which allows for the development of fruits with multiple chambers or compartments. This type of placentation is often associated with fruits that split open to release the seeds, such as capsules or follicles.

The position of the ovules also affects the distribution of seeds within the fruit. In parietal placentation, the seeds are typically arranged along the inner wall of the ovary, resulting in a more dispersed distribution compared to axile placentation, where the seeds are clustered around a central axis.

V. What are some examples of plants with Parietal Placentation?

Parietal placentation is commonly found in a wide range of dicotyledonous plants. Some examples of plants with parietal placentation include:
– Primrose (Primula): where the ovules are attached to the inner wall of the ovary in a single row.
– Lily (Lilium): where the ovules are attached along the margin of the ovary.
– Mustard (Brassica): where the ovules are attached to the inner wall of the ovary in two rows.

These plants exhibit different types of parietal placentation, each with its own unique characteristics and implications for fruit development.

VI. What are the advantages and disadvantages of Parietal Placentation?

Parietal placentation offers several advantages and disadvantages for plants. Some of the advantages include:
– Increased seed dispersal: Parietal placentation allows for a more dispersed distribution of seeds within the fruit, which can enhance seed dispersal and colonization of new areas.
– Efficient pollination: The arrangement of ovules along the inner wall of the ovary can facilitate efficient pollination and fertilization of the ovules.

However, there are also some disadvantages associated with parietal placentation, such as:
– Limited seed protection: The seeds in parietal placentation may be more exposed to external factors, such as predators or environmental conditions, compared to axile placentation.
– Limited seed storage: The dispersed distribution of seeds within the fruit may limit the amount of nutrients and resources available for seed development.

Overall, parietal placentation is an important aspect of plant reproduction that influences fruit development and seed dispersal in dicotyledonous plants.