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Types of Ovule

An Ovule is a part of the female reproductive system in plants. It is the part where female reproductive cells are made and kept, which, after fertilization, turn into seeds. In this article, we are going to look at the components and types of the ovule in detail.

What is Ovule 

The Ovule plays an essential role in plant reproduction. After fertilization, the Ovule swells & then hardens, turns into a seed. Ovary around it grows and turns into fruit.

There are some exceptional cases where the Ovule turns into a fruit. Example: Avocado & Kiwi.

Components of an Ovule

The plants’ Ovule is made up of female gametophytes;

  1. Nucellus
  2. Integuments

Nucellus

The nucellus is the most significant part of the Ovule. It contains the embryo sac and nutritive tissue.

The nutritive tissue remains even after fertilization providing nutrients to the embryo.

Integuments

Integuments are a protective tough layer inside the Ovule. This encloses the nucellus but leaves a small gap known as micropyle.

In gymnosperms, there is only one integument, while the angiosperms have two integuments.

Ovule in gymnosperms & angiosperms
Ovule in gymnosperms & angiosperms (Source)

Types of plants Ovule

Types of Ovule

There are six types of Ovules; these differ based on their shape.

Types of Ovule
Types of Ovule (Source)

Orthotropous or Atropous

In Orthotropous, the plant Ovule is aligned straight such that the Chalaza, the Funicle & the micropyle align.

Example: Polygonum

Anatropous

In Anatropous, the Ovule gets completely inverted during the development period such that the micropyle lies near the hilum.

Example: Pisum

Hemi-Anatropous

In Hemi-Anatropous, the Ovule takes a right angle shape with respect to the Funicle.

Example: Ranunculus

Campylotropous

Campylotropous is a bent shape Ovule, and the alignment between Chalaza and micropyle ceases to exist, making the embryo sack slightly curved.

Example: Brassica

Amphitropous

In Amphitropous, the Ovule is completely curved and forms a shape like a horseshoe.

Example: Poppy

Circinotropous

In Circinotropous, the Funicle wraps around the Ovule in a circle, and the micropyle ultimately points upwards. 

Example: Opuntia 

FAQs

What is an Ovule?

An Ovule is a part of the female reproductive system in plants. It is the part where female reproductive cells are made and kept, which, after fertilization, turn into seeds.

Where is the Ovule found?

In flowering plants, the Ovule is located inside the gynoecium. The ovary of the gynoecium produces one or more Ovules.

What are the types of Ovule?

There are six types of Ovule: Orthotropous, Anatropous, Hemi-Anatropous, Campylotropous, Amphitropous and Circinotropous.

What are the Ovule components?

The plant’s Ovule is made up of female gametophytes; those are Nucellus and Integuments.

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