The word “Gymnosperm” comes from the Greek words “gymnos”(naked) and “sperma”(seed), hence “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. Gymnosperms belong to kingdom ‘Plantae’ and subkingdom ‘Embryophyta’. The fossil evidence suggested that they originated during the Paleozoic era, about 390 million years ago.
Basically, Gymnosperms are the plants in which the ovules are not enclosed by the ovary wall unlike the angiosperms. It remains exposed before and after fertilization, and before developing into a seed. The stem of a gymnosperm can be branched or unbranched. The thick cuticle, needle-like leaves, and sunken stomata on the leaves reduce the rate of water loss in these plants, as shown in the image below.
Characteristics of Gymnosperms-
- They do not produce flowers but form seeds.
- They are not fruit-bearing plants.
- They are mostly pollinated by the wind.
- They form cones with reproductive structures.
- They develop needle-like leaves and are usually found in dry places.
- These plants have vascular tissues which help in transportation of nutrients and water.
Classification of Gymnosperms
Gymnosperms are classified into four types as given below –
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. There are also members that have adapted to dry arid conditions and some also have adapted to oxygen-poor swampy environments. Cycads are dioecious (meaning: individual plants are either all male or female).
Another class of Gymnosperms, Ginkgophyta has only one living species. All other members of this class are now extinct. The Ginkgo trees are characterised by their large size and their fan-like leaves. Also, Ginkgo trees have a large number of applications ranging from medicine to cooking. 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. In fact, 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.
Just like the other members of gymnosperms, Gnetophytes are relics from the past. Today, only three members of this genus exists. Gnetophytes usually consists 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. And furthermore, Gnetophytes differ from other members of this class as they possess vessel elements in their xylem.
These are the most commonly known species among the gymnosperms. They are evergreen, hence they don’t shed their leaves in the winter. These are mainly characterized by male and female cones which form needle-like structures. Coniferous forests 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.
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