Gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes. The word Gymnosperm comes from the Greek words gymnos, Which means naked and Sperma, Means seed, Hence known as Naked seeds. They 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.
Gymnosperms are plants in which the ovules are not enclosed within the ovary wall, unlike the angiosperms. It remains exposed before and after fertilization, and before developing into a seed. The stem of gymnosperms can be branched or unbranched. The thick cuticle, needle-like leaves, and sunken stomata reduce the rate of water loss in these plants.
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.
- 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.
Classification of Gymnosperms
- Cycadophyta: Cycads are seed-bearing plants where the majority of the members are now extinct. They had flourished during the Jurassic and late Triassic era. Nowadays, the plants are considered as relics from the past. These plants usually have large compound leaves, thick trunks and small leaflets which are attached to a single central stem. They range in height anywhere between a few centimeters to several meters. Cycads are usually found in the tropics and subtropics. Some members have adapted to dry arid conditions, and some also have adapted to oxygen-poor swampy environments.
- Ginkgophyta: Ginkgo leaves are ingested as a remedy for memory-related disorders like Alzheimer’s. Ginkgo trees are also very resistant to pollution, and they are resilient against diseases and insect infestations. They are so resilient that after the nuclear bombs fell on Hiroshima, six Ginkgo trees were the only living things to survive within a kilometer or two of the blast radius.
- Gnetophyta: Just like any other member of gymnosperms, Gnetophytes are also relics from the past. Today, only three members of this genus exist. Gnetophytes usually consist of tropical plants, trees, and shrubs. They are characterized by flowery leaves that have a soft coating. This coating reveals an ancestral connection with the angiosperms. Gnetophytes differ from other members of this class as they possess vessel elements in their xylem.
- Coniferophyta: These are the most commonly known species among the gymnosperm family. They are evergreen; hence they do not shed their leaves in the winter. These are mainly characterized by male and female cones that form needle-like structures. Coniferous trees are usually found in temperate zones where the average temperature is 10 ℃. Giant sequoia, pines, cedar, and redwood are one of the many examples of Conifers.
Examples of Gymnosperms