Gymnospermae

Together with flowering plants Angiosperms, the Gymnosperms form the group Spermatophyta (sperma means seed and phyte means plant) - seed-producing plants.

The gymnospermae bear naked ovules on flat scale leaves called ovuliferous scales which are not enclosed in carpels (ovary). The ovuliferous scales are arranged in cones.

Characteristics of Gymnosperms

1. The adult plant (sporophyte) is a tall, woody, perennial tree or shrub mostly evergreen. The stem is usually branched, but rarely unbranched as in Cycas.

2. Leaves may be simple (as in Pinus) or compound (as in Cycas).

3. Leaves may be dimorphic or of one kind only. Foliage leaves are large green simple or pinnately compound, needle-like and grow on dwarf shoot as in Pinus, or directly borne on the main trunk as in Cycas. Scale leaves are brown and simple.

4. Vascular bundles in stem are arranged in a ring and show secondary growth.

5 Gymnosperms bear cones which are usually unisexual (either male or female), rarely bisexual as in Gnetum.

6. Pollen grains are haploid produced in microsporangia of the male cones. In Pinus, each pollen grain has two large sacs, called wings to help in the dispersal by wind. Pollen grains produce two male gametes.

7. Ovules are not enclosed in ovary as in Angiosperms, but are borne naked on leafy megasporophylls of female cone, so the term gynmosperms or naked seeds for this group. Ovules are produced side by side, inside which female gamete or egg is produced. The male gamete fuses with female gamete in the ovule. The fertilised ovule then develops into a seed (winged in case of Pinus).

Some common Gymnosperms

Pine (Pinus), Redwood (Sequoia), Juniper (Juniperus), Cedar (Cedrus) and sagopalm (Cycas). Many gymnosperms yield timber, resins, turpentine, and several other products like the dry fruit chilgoza. Sago (sabut dana) is obtained from old stems of Cycas.