What is the Difference Between Anatropous and Orthotropous Ovule?

The main difference between anatropous and orthotropous ovules lies in their orientation and the position of the micropyle with respect to the funicle and other structures. Here are the key differences:

Anatropous Ovule:

Inverted or curved structure.
Micropyle, chalaza, and funicle lie in the same line.
Micropyle is located at the bottom, near the funicle.
Body of the ovule fuses with the funicle.
Most common type of ovule orientation, found in more than 80% of angiosperms.
Common in monocots and dicots.
In some cases, anatropous ovules are partly inverted, known as amphitropous ovules (90° inversion).

Orthotropous Ovule:

Straight structure with no curvature.
Micropyle, nucleus, chalaza, and funicle all lie in a straight line.
Micropyle is located at the apex region.
Funicle does not fuse with the ovule body.
Less common compared to anatropous ovules.
Primarily observed in plant families like Piperaceae and Polygonaceae.

In summary, anatropous ovules are more common and have an inverted or curved structure, while orthotropous ovules have a straight structure and are less abundant.

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What is the Difference Between Anatropous and Orthotropous Ovule?

Comparative Table: Anatropous vs Orthotropous Ovule

Here is a table comparing the differences between anatropous and orthotropous ovules:

Feature	Anatropous Ovule	Orthotropous Ovule
Structure	Completely curved or inverted	Straight, without any curvature
Micropyle Position	Located at the bottom	Located at the apex
Hilum Position	Micropyle and hilum lie close to each other	Micropyle, hilum, and chalaza lie in one line
Funicle Fusion	Body of the ovule is fused with the funicle on one side	Funicle is not fused with the ovule body
Occurrence	Most common type of ovule orientation, found in more than 80% of angiosperms	Less abundant compared to anatropous, observed in plant families like Piperaceae and Polygonaceae

Anatropous ovules are characterized by their inverted structure, with the micropyle tip directed towards the placenta and the chalazal end positioned at the top. In contrast, orthotropous ovules maintain a straight structure with the micropyle located at the apex.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.