Orthotropous Ovule

- An ovule is a structure present in the ovary of a flower that contains the female reproductive cells or gametophyte.
- The ovule is attached to the ovary wall by a stalk-like structure called a funiculus.
- The ovule has three main parts: the chalaza, the micropyle, and the embryonic sac.
- The chalaza is the base of the ovule where the funiculus is attached.
- The micropyle is a small opening in the ovule through which the pollen tube enters during fertilization.
- The embryonic sac, also known as the female gametophyte, is the part of the ovule that contains the egg cell.
- In an orthotropous ovule, the funiculus, embryonic sac, chalaza, and micropyle all lie in a straight line.
- This is the simplest type of ovule, and is found in most gymnosperms and some angiosperms.
- In an orthotropous ovule, the embryonic sac is positioned at the base of the ovule, and the micropyle is at the top.
- The orthotropous ovule is also known as an erect ovule.
- Examples of plants that have orthotropous ovules include beans, peas, and lilies.

Amphitropous, Campylotropous, and Anatropous Ovules

- Amphitropous, campylotropous, and anatropous ovules are three other types of ovules.
- In an amphitropous ovule, the funiculus is curved, and the embryonic sac is bent back on itself.
- In a campylotropous ovule, the funiculus is curved, and the embryonic sac is curved so that the micropyle and chalaza are close together.
- In an anatropous ovule, the funiculus is attached to the ovule at the top, and the embryonic sac hangs down from it.
- The micropyle is at the bottom of the ovule, and the chalaza is at the top.
- Examples of plants that have anatropous ovules include apples, pears, and strawberries.

Conclusion

- In summary, when the funiculum, embryo sac, chalaza, and micropyle lie in one straight line, the ovule is called an orthotropous ovule.
- This is the simplest type of ovule, and is found in most gymnosperms and some angiosperms.
- Other types of ovules include amphitropous, campylotropous, and anatropous ovules, which have different shapes and orientations.

Orthotropous Ovule

An ovule is part of the female reproductive system of a plant that develops into a seed after fertilization. The position of the ovule within the ovary of the flower determines its orientation.

Orthotropous ovules are straight, with the funiculum, embryo sac, chalaza, and micropyle aligned along a common axis. The ovule’s shape is elongated and almost cylindrical. This ovule position is considered the most primitive and is found in many primitive angiosperms, gymnosperms, and pteridophytes.

Characteristics of Orthotropous Ovule

The following are the characteristics of Orthotropous ovules:

1. Straight
2. Funicle and hilum are continuous
3. Micropyle and chalaza are at opposite ends
4. Nucellus is straight and elongated
5. Integuments are fused and form a single layer
6. The ovule is attached to the placenta via the funicle

Orthotropous ovules are found in many plant families, including Orchidaceae, Liliaceae, and Iridaceae.