Gymnosperms – Definition, Characteristics, Uses and Examples
Gymnosperms are a group of seed-bearing plants that do not produce flowers or fruits. Gymnosperms are not surrounded by fruit. Gymnosperms are believed to have first appeared during the Carboniferous period and became the dominant land plants during the Mesozoic era.
What are Gymnospermae?
Gymnosperm word originates from the greek language (gymnos-naked; Sperma-seed) i.e., Naked Seed. Gymnosperms plants produce the seed but without fruits like in angiosperms. One of the characteristics of gymnosperms is their seeds, which are typically exposed on the surface of cones or in a naked condition. This is in contrast to angiosperms (flowering plants), which enclose their seeds within fruits. Gymnosperms also have vascular tissue that transports water and nutrients throughout the plant and typically has needles or scales as leaves.
Gymnosperms is a subtype of the Plant Kingdom, and the subkingdom is Embryophyta. Some fossil records give evidence that the gymnosperm is evolve in the Paleozoic era, around 390 million years ago. The gymnosperm plant ovule is not closed and it remains open whereas the angiosperm ovule is covered with ovary. To decrease the transpiration rate gymnosperm plant leaves are need-like, sunken stomata over the leaf.
Characteristics of Gymnosperms
Mentioned below are the characteristics of gymnosperm:
- They are the most primitive and simple seed plants.
- The seeds produced by these plants are naked and are not enclosed within fruits.
- Usually perennial, evergreen, and woody plants, are present in colder areas.
- Gymnosperms usually have needle-like leaves.
- Sporophylls are aggregated to form cones. These are separate male and female cones.
- Xylem lacks vessels and the phloem lacks companion cells.
- The plant body is saprophytic and is differentiated into roots, stems, and leaves.
- Leaves are generally spirally arranged. They may be whorled as in Cedrus or opposite and decussate as in Gnetum.
- Vegetative methods of reproduction are rare in gymnosperms. Cycads do propagate through bulbils.
- Pollination is direct i.e., pollen grains come in contact in direct contact with the ovule.
- All gymnosperms are wind-pollinated because stigma is absent in gymnosperms.
- The number of cotyledons in a seed is one or two as in Cycas or many as in Pinus.
Classification of Gymnosperms
Gymnosperms are classified into 4 types. Each group is distinguished by its unique characteristics, and they all play important ecological roles in their respective habitats, those are:
Cycads are dioecious (meaning: individual plants are either all male or female). Cycads are seed-bearing plants and most of the individuals are presently extinct. They grow during the Jurassic and late Triassic times. These days, plants are considered relics from past times.
These gymnosperms plants generally have big compound leaves, thick trunks, and little pamphlets which are connected to a central stem. They range in level from any place between some centimeters to a few meters. Cycads are generally seen in the tropics and subtropics region. Some Cycadophyta is adapted to dry conditions and some likewise have adjusted to oxygen-poor damp conditions. Examples: Cycas, Zamia, Zamiaceae.
Only one, Ginkgophyta is a living animal group. Any remaining individuals from this class are extinct. The Ginkgo trees are described by their big size and their fan-like leaves. Likewise, Ginkgo trees have an enormous number of uses going from medication to cooking. Ginkgo leaves are ingested as a solution for memory-related diseases like Alzheimer’s.
Gnetophytes are additionally relics from an earlier time. Today, just three individuals from this family exist. Gnetophytes typically comprise tropical plants, trees, and shrubs. They show the phenotype of colorful leaves that are covered with a soft coating. This cover tells a hereditary association with angiosperms. Gnetophytes vary from different individuals from this class as they have vessel components in their xylem. Example: Ephedra, Gnetum.
These are the most ordinarily known species among the gymnosperm family. They are evergreen; consequently, in winters they don’t shed their leaves. These are essentially described by male and female cones with structures like a needle. Coniferous trees are normally found in temperate zones where the typical temperature is 10 ℃. Monster sequoia, pines, cedar, and redwood are instances of Conifers. Examples: redwood trees, junipers, cypress trees, tidy trees, and hemlocks.
Some examples of gymnosperms are:
Gymnosperm Life Cycle
Gymnosperm plants have both haploid and diploid life cycles that is they reproduce via generation alteration. The life cycle of gymnosperms involves a complex process of alternation between two generations, the sporophyte, and the gametophyte. Gymnosperm have sporophyte-dominant life cycle.
Gymnosperms are heterosporous plants i.e., plants produce spores that are haploid microspores or megaspores. The gametic phase of the gymnosperm is short.
Reproduyctive organ of gymnosperms are:
- Male Cones: The male cones of gymnosperms develop from the sporophyte. They contain the male gametophyte, which produces pollen grain. Microsporangium forms microspores that are haploid in structure, some microspheres develop into pollen grains and others degrade.
- Female Cones: The female cones of gymnosperms develop from the megasporophylls. Megasporangium contains the female ovule, which produces megaspores.
Once the pollen reaches the female cones via wind or any pollinating agent, it fertilizes the eggs, resulting in the formation of a diploid zygote. The zygote develops into an embryo, which is enclosed in a seed. The seed is then dispersed and can grow into a new sporophyte plant.
The life cycle of gymnosperms is different from that of angiosperms because gymnosperms do not produce flowers or fruits. Instead, they produce cones and seeds that are usually exposed. The life cycle of gymnosperms is an essential process that ensures the continued growth and reproduction of these plants.
Importance of Gymnosperms
- Conifers and other gymnosperms are economically essential.
- Conifers are used in paper, furniture, and in lumber production.
- Paclitaxel is a commonly available anticancer drug derived from gymnosperms.
- Gymnosperms are a good source of food.
FAQs on Gymnosperms
Q1: What is a gymnosperm plant?
Gymnosperms ar a subtype of plants in which the seed is not covered with the fruit. Those plants are classified under gymnosperms.
Q2: What is gymnosperm vs. angiosperms?
Angiosperms are plants having seeds capsulated with the fruit, while plants not covered with fruit are known as gymnosperms.
Q3: Do gymnosperm produce pollen?
Yes, gymnosperm produce pollen i.e. male gametes, normally known as male cone.
Q4: What are some examples of gymnosperms?
Examples of gymnosperms include conifers, cycads, ginkgoes, and gnetophytes.
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