Features of Gymnosperms

A gymnosperm is any vascular plant that reproduces through an exposed seed, or ovule, as opposed to angiosperms, or flowering plants, whose seeds are enclosed by mature ovaries, or fruits. Many gymnosperm seeds (literally, “naked seeds”) are borne in cones and are not visible until the plant matures. Taxonomists recognise four distinct divisions of extant (non-extinct) gymnospermous plants: Pinophyta, Cycadophyta, Ginkgophyta, and Gnetophyta, with 88 genera and over 1,000 species distributed worldwide.

Gymnosperms were dominant during the Mesozoic Era (about 252.2 million to 66 million years ago) when some modern families evolved (Pinaceae, Araucariaceae, Cupressaceae). Even though since the Cretaceous Period (about 145 million to 66 million years ago).

The life cycle of gymnosperm

Plants in the gymnosperm life cycle alternate between sexual and asexual phases. This type of life cycle is referred to as generational alternation. Gamete production occurs during the cycle’s sexual phase or gametophyte generation. Spores are produced during the asexual phase, also known as sporophyte generation. 

The sporophyte generation is the dominant phase of the plant life cycle in vascular plants, as opposed to non-vascular plants.

The plant sporophyte is recognised in gymnosperms as the bulk of the plant itself, including roots, leaves, stems, and cones. The sporophyte is in charge of producing haploid spores via the meiotic process. Spores, which have one complete set of chromosomes, develop into haploid gametophytes.

Features of Gymnosperms

• Gymnosperms have evolutionary significance and some distinguishing characteristics. The absence of flowers and the presence of naked, open seeds distinguish them. Because they lack flowers, fruits are also lacking in this group of plants.

• The wind is the primary source of pollination and dispersal. These are mostly medium to large trees, with a few shrub species thrown in for good measure. The Sequoia is a gymnosperm, and it is one of the tallest tree species.

• The plant body differs in that it is divided into leaves, stems, and roots. The needle-like leaves have a thick cuticle and sunken stomata, as seen in conifers. This feature aids in lowering water loss due to transpiration.

• Some plants, such as Pinus, have these roots associated with fungi and form mycorrhiza. While the roots of a few other species, such as the Cycas plant, are in the form of specialised roots known as coralloid roots and are associated with nitrogen-fixing cyanobacteria. These plants are vascular as well, with both xylem and phloem present.

Reproduction and Fertilization in Gymnosperms

Strobilus, also known as a cone, is the reproductive structure of gymnosperms. Male and female strobili can coexist on the same tree (as seen in Pinus) or on different trees (seen in Cycas). Gymnosperm plants have heterosporous spores. They produce two types of spores: haploid microspores and megaspores.

• Male Cones: Male strobili, also known as male cones, have microsporophylls, which contain microsporangia that produce haploid microspores. Some of these microspores mature into male gametes known as pollen grains, while the remainder degenerates.

• Female Cones: Megasporophylls that form a cluster are known as female strobili or cones. They are the carriers of the megasporangium ovules. As a result, haploid megaspores and a megaspore mother cell are produced.

• Fertilization: occurs when pollen grains are released from the microsporangium and are carried by the wind to the female cones. The pollen grain forms a pollen tube that grows towards the archegonium.

Characteristics of Gymnosperms

Gymnosperms are seed plants that have adapted to land life; as such, they are autotrophic, photosynthetic organisms that conserve water. They have a vascular system (used for water and nutrient transportation) that includes roots, xylem, and phloem. The term gymnosperm refers to a “naked seed,” which is the primary distinction between gymnosperms and angiosperms, two distinct subgroups of seed plants. The term derives from the fact that gymnosperm ovules and seeds develop on the scales of cones rather than in enclosed chambers known as ovaries.

On the evolutionary scale, gymnosperms are older than angiosperms. They appear in the fossil record much earlier than angiosperms. The various environmental adaptations that gymnosperms have to represent a step forward.

What is Gnetophyta?

Gnetophyta is a gymnosperm division with 65 species found in three genera: Ephedra, Gnetum, and Welwitschia. Many Ephedra species are shrubs that can be found in desert regions of the Americas or the high, cool regions of India’s Himalayan mountains. Certain Ephedra species are medicinal and are the source of the decongestant drug ephedrine. The leaves of Ephedra species are scale-like and have slender stems.

Some Gnetum species are shrubs and trees, but the majority are woody vines that climb around other plants. They live in tropical rain forests and have broad, flat leaves that look like flowering plant leaves. Male and female reproductive cones are found on separate trees and resemble flowers.

Conclusion

Many gymnosperm seeds are borne in cones and are not visible until the plant matures. The sporophyte generation is the dominant phase of the plant life cycle in vascular plants, as opposed to non-vascular plants. The plant sporophyte is recognised in gymnosperms as the bulk of the plant itself, including roots, leaves, stems, and cones. The absence of flowers and the presence of naked, open seeds distinguish them. The Sequoia is a gymnosperm, and it is one of the tallest tree species. While the roots of a few other species, such as the Cycas plant, are in the form of specialised roots known as coralloid roots and are associated with nitrogen-fixing cyanobacteria.