1. Sequoia sempervirens: Sequoia sempervirens is a gymnosperm. Its height is 115.92 meters or 380.3 feet. Redwood National Park, California, USA.
2. Shorea faguetiana: Shorea faguetiana is an herbaceous plant. Its height is 100.8 meters or 331 feet. Borneo, Indonesia, Asia.
3. Eucalyptus regnans: Eucalyptus regnans is an herbaceous plant. Its height is 99.82 meters or 329.7 feet. Tasmania, Australia.

The leaves of gymnosperms have special markings on the stems when they fall in a storm. This special mark is called leaf scar. Leaf scar is a heterogeneous feature of gymnosperms.

1. Gymnosperms are green, autophagous and evergreen.
2. The main plants are sporophytes and shoots.
3. Their body is divided into roots, stems and leaves.
4. They have two types of leaves. Brown bracts and green foliage.
5. Their leaves are pointed (Pine) and compound type (Cycas).
6. The plant has leaf scars.
7. Their flowers are simple and unisexual.
8. Flowers have microsporophylls or spores and megasporophylls or spores.
9. Their flowers do not have uterus, uterus and uterus.
10. During pollination, the pollen grains fall directly into the ovule opening.
11. As the flower does not have a uterus, the fruit does not form.
12. As the fruit does not develop, the seeds are naked or expressed.
13. Their seeds are haploid and formed before fertilization.
14. Their seeds germinate to form diploid sporophyte plants.
15. They do not become double-toxic (Ephedra does).
16. The number of cotyledons in their embryos is one, two (Cycas) or more (Pinus).
17. They are air pollinated. That is, pollination occurs through wind.
18. Vascular bundles are free, parallel and annular.
19. Xylem does not contain vessel cells (Gnetum does) and phloem lacks companion cells.
20. They are archegoniates. That is, archegonia create.
21. They are heterosporous. That is, two or more types of spores are produced.
22. Most of their species are terrestrial and tropical.
23. Asymmetric or heteromorphic genes exist in the life cycle.

There are about 70 species in the Gnetophyta division. They have most similarities with herbaceous plants. Their leaves are similar to herbaceous plants. They have vessels in their xylem and spermatozoa are without flagella. The Welwitschia plant has two leaves and flower-like pods (Welwitschia is found in the Namibian desert). Double fertilization occurs in Ephedra plants of this category. The respiratory medicine ephedrine is obtained from the Ephedra plant.

Coniferophyta contains 550 species in 6 families. The temperate Northern Hemisphere has conifer forests. Russia has conifer forests. The world’s largest conifer forest is located in Siberia and is the world’s largest biome. Bristlecone pine is the oldest tree in the world. Its age is 5000 years. It is found in Navana and California. The tallest trees in the world are Hyperion (Sequoia sempervirens) at ± 400 feet and Coast Redwood (Sequoia gigantea) at 324 feet.

Plants of Cycadophyta division are called cycads. This 200 million year old division survives today with 100 species. They are woody plants like palm trees. Their leaves resemble leathery feathers. Their sperm have flagella. They are widespread in the equatorial region. They grow in dry arid and wet wetlands. The division Cycadophyta consists of three classes. Cycadofilicales, Bennettitales and Cycadales. Zamia pygmaea cycad is the smallest gymnosperm plant in the world. Dr. Siddique Publications

Ginkgo biloba is the only living species of Ginkgophyta. It is the world’s oldest seed plant that has survived on Earth with little change. Their leaves are large and fan-like. Their sperm are flagellated and motile. These plants greatly pollute the environment. They are disease and insect resistant.

Living gymnosperms are divided into 4 categories.
1. Ginkgophyta: Ginkgo biloba is the only living species of Ginkgophyta. It is the world’s oldest seed plant that has survived on Earth with little change. Their leaves are large and fan-like. Their sperm are flagellated and motile. These plants greatly pollute the environment. They are disease and insect resistant.
2. Cycadophyta: Plants of Cycadophyta division are called cycads. This 200 million year old division survives today with 100 species. They are woody plants like palm trees. Their leaves resemble leathery feathers. Their sperm have flagella. They are widespread in the equatorial region. They grow in dry arid and wet wetlands. The division Cycadophyta consists of three classes. Cycadofilicales, Bennettitales and Cycadales. Zamia pygmaea cycad is the smallest gymnosperm plant in the world. Dr. Siddique Publications
3. Coniferophyta: Coniferophyta contains 550 species in 6 families. The temperate Northern Hemisphere has conifer forests. Russia has conifer forests. The world’s largest conifer forest is located in Siberia and is the world’s largest biome. Bristlecone pine is the oldest tree in the world. Its age is 5000 years. It is found in Navana and California. The tallest trees in the world are Hyperion (Sequoia sempervirens) at ± 400 feet and Coast Redwood (Sequoia gigantea) at 324 feet.
4. Gnetophyta: There are about 70 species in the Gnetophyta division. They have most similarities with herbaceous plants. Their leaves are similar to herbaceous plants. They have vessels in their xylem and spermatozoa are without flagella. The Welwitschia plant has two leaves and flower-like pods (Welwitschia is found in the Namibian desert). Double fertilization occurs in Ephedra plants of this category. The respiratory medicine ephedrine is obtained from the Ephedra plant.

Gymnosperms are always terrestrial. They carry frosty features. There are about 12 genera, 83 genera and 721 (some say 1080) species of gymnosperms in the world. 5 species of gymnosperms grow in Bangladesh. Cycas pectinata grows in Bariyadala Hills of Chittagong, Podocarpus nerifolius (Bamboo leaf) grows in Chittagong, Hill Chittagong and Sylhet, Gnetum grows in Chittagong, Hill Chittagong, Sylhet and Cox’s Bazar and Pinus carribeana grows in Chittagong. 3 species of Gnetum grow in Bangladesh. Gnetum latifolium, Gnetum montenum and Gnetum oblongum. Some gymnosperms are Pinus, Aurucaria, Cupressus, Thuja etc.

In 1825, Robert Brown separated gymnosperms from gymnosperms. The father of botany, Theophrastus, first used Gymnosperm in his Inquiry into Plants. Gymnosperms originated in the Devonian Period of the Paleozoic Era 300 million years ago and spread across the globe during the Mesozoic Era. The tallest trees in the world are Hyperion (Sequoia, Sequoia sempervirens) and General Sherman or Redwood Tree (Sequoia, Sequoia gigantea). The oldest tree, the bristlecone pine, is a gymnosperm. Zamia pygmaea is the world’s smallest gymnosperm.