Q.Describe the important characteristics of gymnosperms.

Important characteristics of gymnosperms:

• Their ovules are not enclosed in any ovary wall but sit exposed, and after fertilisation the seeds too remain uncovered — hence the name naked-seeded plants (gymnos meaning naked, sperma meaning seed).
• They are woody plants ranging from shrubs to medium and tall trees, including the giant redwood Sequoia.
• The root is usually a tap root; Pinus roots form mycorrhiza with fungi, and Cycas has coralloid roots that host nitrogen-fixing cyanobacteria.
• Leaves are well adapted to harsh conditions — in conifers they are reduced to needles, with a thick cuticle and sunken stomata to cut water loss.
• They are heterosporous, forming microspores and megaspores in sporangia on microsporophylls and megasporophylls that are arranged in spirals to make male and female cones. …

The name says the most important thing about the group. Gymnos means naked and sperma means seed, and in these plants the ovules are not tucked inside a protective ovary wall — they sit exposed on the plant both before and after fertilisation. Because nothing encloses them, the seeds that form afterwards are also left naked. This single feature, exposed ovules maturing into uncovered seeds, is what separates gymnosperms from the flowering plants.

In form, gymnosperms are woody plants that vary greatly in size, from shrubs through medium-sized trees to tall trees; the giant redwood, Sequoia, is among the tallest trees on Earth. Their root system is generally a tap root, but two special arrangements are worth noting: in Pinus the roots associate with fungi to form mycorrhiza, which helps in absorbing nutrients, and in Cycas some roots become coralloid roots that house nitrogen-fixing cyanobacteria.

The leaves are notable for how well they resist harsh conditions of temperature, humidity and wind. In conifers they are reduced to slender needles, which lowers the exposed surface area, and a thick waxy cuticle together with stomata sunk into pits both work to limit water loss.