Gymnosperms: The word “Gymnosperm” comes from the Greek words “gymnos”(naked) and “sperma”(seed), hence known as “Naked seeds.” Gymnosperms are the seed-producing plants, but unlike angiosperms, they produce seeds without fruits. These plants develop on the surface of scales or leaves, or at the end of stalks forming a cone-like structure.

Characteristics of Gymnosperms

• They do not produce flowers.
• Seeds are not formed inside a fruit. They are naked.
• They are found in colder regions where snowfall occurs.
• They develop needle-like leaves.
• They are perennial or woody, forming trees or bushes.
• They are not differentiated into ovary, style and stigma.
• Since stigma is absent, they are pollinated directly by the wind.
• The male gametophytes produce two gametes, but only one of them is functional.
• They form cones with reproductive structures.
• The seeds contain endosperm that stores food for the growth and development of the plant.
• These plants have vascular tissues which help in the transportation of nutrients and water.
• Xylem does not have vessels and the phloem has no companion cells and sieve tubes.
• They reproduce by following methods:
  • Produces haploid microspore and megaspore
  • The male and female do not have an independent existence.
  • The transfer of pollens (pollination) is via air, and the zygote develops into embryos. The embryos then develop into naked seeds.

The life cycle of gymnosperms is both haploid and diploid, i.e., they reproduce through the alternation of generations. They have a sporophyte-dominant cycle.

The gametophyte phase is relatively short. The reproductive organs are usually cones.

Male Cones– These have microsporophylls that contain microsporangia. Microsporangium produces haploid microspores. A few microspores develop into male gametes called pollen grains, and the rest degenerate.

Female Cones– The megasporophylls cluster together to form female cones. They possess ovules containing megasporangium. It produces haploid megaspores and a megaspore mother cell.

The pollen reaches the egg through wind or any other pollinating agent, and the pollen grain releases a sperm. The nuclei of male and female gametophytes fuse together to form a zygote. This is known as fertilisation.

The seed appears as scales which can be seen on the cones of the gymnosperm.

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By Team Learning Mantras