Evoluation of seed habit in plants

The evolution of seed habit is a significant milestone in the plant kingdom. It allowed plants to reproduce and spread in diverse environments, leading to the development of various plant groups. The evolution of seed habit can be observed in several plant groups, including gymnosperms and angiosperms.

Gymnosperms
Gymnosperms are a group of plants that evolved approximately 360 million years ago and played a crucial role in the evolution of seed habit. They include cone-bearing plants such as pines, spruces, and cycads. The key features of gymnosperms include:

1. Naked Seeds: Gymnosperms have seeds that are not enclosed within a fruit. Instead, they are usually borne on the surface of cones or other structures.

2. Pollination: Gymnosperms rely on wind or insects for pollination. The male cones produce pollen grains that are carried by wind or insects to reach the female cones, where fertilization takes place.

3. Embryo Protection: The seeds of gymnosperms have protective coverings that help in protecting the developing embryo. This protective covering is often a tough seed coat that provides resistance against environmental conditions.

Angiosperms
Angiosperms, also known as flowering plants, are the most diverse and dominant group of plants on Earth today. They evolved approximately 125 million years ago and possess several key features that contribute to the evolution of seed habit:

1. Enclosed Seeds: Angiosperms have seeds that are enclosed within a fruit. The fruit develops from the ovary of the flower and serves as a protective structure for the developing seed.

2. Flowering and Pollination: Angiosperms have evolved flowers, which are specialized structures for sexual reproduction. These flowers attract pollinators such as insects, birds, or bats, which aid in the transfer of pollen from the male to the female reproductive organs.

3. Double Fertilization: Angiosperms exhibit a unique reproductive mechanism called double fertilization. This process involves the fusion of two sperm cells; one fertilizes the egg to form the embryo, while the other combines with other cells to form endosperm, a nutritive tissue for the developing embryo.

Conclusion
The evolution of seed habit in plants has greatly contributed to the success and diversity of plant life on Earth. Gymnosperms and angiosperms are two major plant groups that exhibit the evolution of seed habit. While gymnosperms have naked seeds and rely on wind or insects for pollination, angiosperms have enclosed seeds within fruits and employ flowers for pollination. Understanding the evolution of seed habit helps in comprehending the complexity and adaptability of plants in different environments.