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Gymnosperms – Definition, Characteristics, Uses and Examples

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  • Last Updated : 02 Aug, 2022
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Each organism in this world, whether it is a plant, an animal, or a microorganism(viruses, bacteria, unicellular eukaryotes), is unique in itself. This uniqueness of individuals forms the basis of the diversity among living organisms.

The term “biodiversity” is a combined form of biological Diversity“. It is coined by Walter G.Rosen in 1986. A large variety of organisms or terms used to refer to the number of varieties of plants and animals on earth is termed biodiversity. There are three types of biodiversity: genetic, species, and ecological diversity. Diversity extends to the habitat, habits, nutrition, forms, etc., of different organisms. Different varieties of flora and fauna are present all over the world.

Living organisms have been classified variously according to different criteria, however, the two systems are most in use: 1. Two-kingdom system of classification 2.Five-kingdom system of classification. The Kingdom Plantae of this classification is further divided into various divisions based on various criteria. The division Spermatophyta includes all seed-bearing plants. It has been divided into two sub-divisions- Gymnosperms and Angiosperms.

Gymnospermae

General Characters of Gymnosperms(gymnos-naked; sperma-seed)

  1. They are the most primitive and simple seed plants.
  2. The seeds produced by these plants are naked and are not enclosed within fruits.
  3. Usually perennial, evergreen, and woody plants.
  4. Sporophylls are aggregated to form cones. These are separate male and female cones.
  5. Xylem lacks vessels and phloem lacks companion cells.
  6. The plant body is saprophytic and is differentiated into roots, stem, and leaves.
  7. The presence of leaf scars on the stem is a characteristic feature of gymnosperms.
  8. Leaves are generally spirally arranged. They may be whorled as in Cedrus or opposite and decussate as in Gnetum.
  9. Vegetative methods of reproduction are rare in gymnosperms. Cycads do propagate through bulbils.
  10. Pollination is direct i.e., pollen grains come in contact in direct contact with the ovule.
  11. All gymnosperms are wind-pollinated.
  12. The number of cotyledons in a seed is one or two as in Cycas or many as in Pinus.
Gymnosperm

 

Affinities of Gymnosperms

Gymnosperms are considered to form a bridge between pteridophytes and angiosperms. Thus, they share many features with these groups. Given below are affinities of gymnosperms with pteridophytes and angiosperms:

Affinities of Gymnosperms with Pteridophytes

Similarities

  1. Both these groups show distinct alternation of generations with a dominant saprophytic phase.
  2. The saprophytic plant body is differentiated into roots, stems, and leaves.
  3. The leaves of gymnosperms show circinate vernation like those of ferns. They are pinnately compound in both groups.
  4. Xylem in both these groups lacks vessels. Phloem is devoid of companion cells.
  5. In some groups of gymnosperms, such as Cycadales and Ginkgoales, male gametes are motile and flagellate as in that of pteridophytes.

Dissimilarities

  1. Gymnosperms are mostly trees, whereas pteridophytes are usually perennial herbs or shrubs.
  2. Pteridophytes usually grow in moist, shady, and terrestrial places, while gymnosperms occur in xerophytic habitats.
  3. pteridophytes possess adventitious roots, whereas gymnosperms have a long-lasting tap root system.
  4. The mature metaxylem, in most gymnosperms, shows bordered pits. In most pteridophytes, the xylem is typically scalariform.
  5. Gymnosperms are seed-bearing plants. seed formation is absent in pteridophytes.

Affinities of Gymnosperms with Angiosperms

Similarities

  1. sporophyte is differentiated into root, stem, and leaves.
  2. The vascular system of the stem consists of conjoint collateral and open vascular bundles.
  3. The stem increases in girth by secondary growth.
  4. Like gymnosperms, many angiosperms are also wind-pollinated.
  5. The gametophytic phase is reduced in both groups.

Dissimilarities

  1. Gymnosperms are mostly woody trees, but angiosperms have a variety of habit trees, shrubs, or herbs.
  2. The strobili of gymnosperms are usually unisexual, whereas the flowers of angiosperms are mostly bisexual.
  3. The ovules of gymnosperms whereas those of angiosperms remain enclosed within the ovary wall.
  4. In female gametophyte of gymnosperms, archegonia are present, but they are not found in angiosperms.
  5. Double fertilization and triple fusion, found in angiosperms, do not occur in gymnosperms.

Uses 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.

Frequently Asked Questions

Question 1: When did primitive gymnosperms originate?

Answer:

In the Triassic period of the Mesozoic era, primitive gymnosperms originate.

Question 2: Write two characteristics of the ovule of gymnosperms?

Answer:

Ovules of gymnosperms are orthotropus and unitegmic.

Question 3: Describe the distinguishing features of gymnosperms.

Answer:

Gymnosperms are naked and are found in colder regions where snowfall occurs. They develop needle-like leaves. they are woody forming trees or bushes.

Question 4: Write the examples of gymnosperms.

Answer:

Examples of gymnosperms include conifers, cycads, ginkgoes, and gnetophytes.

Question 5: Write two similarities between the gymnosperms and the angiosperms.

Answer:

  • Vessels and companion cells also occur in some gymnosperms like angiosperms. 
  • In both groups, ovules develop into seeds.
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