Gymnosperms encompass all seed plant life that is not an angiosperm. Angiosperms form flowers and therefore fruit. Gymnosperms have exposed seeds and do not flower or fruit. The name comes from the Greek word gymno, which means naked. Combined with sperm and it means naked seed or anything that has no enclosed seed structure. Cones and leaves may bear the seed and they have ovules, but they are not enclosed ovaries like those in flowers.
It all comes down to sex. Most plants have male and female parts and both are required to produce offspring. The male produces pollen, which in turn fertilizes the female. She then produces seed. In gymnosperms, the sexes are always separate with the male and female gametophytes sometimes on different plants. These are held in cones or other structures but are not entirely enclosed. When seed is formed in the female structures, it is easily pollinated by the male, who produces a pollen dust and then slips out of the cone.
Flowers are what produces fruit. The ovary swells once the plant has been pollinated and grows into a structure that houses the seeds. Gymnosperm cones are the flower of conifers, cyads, ginkgoes and a few other species. Instead of an ovary, the female cones have ovules located at the base of each scale. The ovules have a small hole at the end to allow the pollen to enter. After pollination, the ovule is fertilized and then begins division. This process may take up to a year.
The resulting fertilized ovule does not develop into a fruit as it would in an angiosperm. Because gymnosperms have no ovary, they can never produce fruit. Seeds develop from the ovules that are found in the developed ovaries or fruit, but in the case of gymnosperms, the ovules are located directly on the surface of the flower or cone. Yews and ginkgoes develop fruitlike structures, but their seed is not inside these organs, which makes them gymnosperms.
The seeds of most gymnosperms are wind-pollinated with the exception of cyads, which are pollinated by beetles. The male gametophyte is transferred to the female, and once fertilization is complete, it becomes a zygote. The zygote must undergo meiosis to transform into a seed. A seed is simply an embryo with some nutrient matter and a shell or coating. Since the seed is not held inside a fruiting body, it doesn't have to wait to be eaten or crushed to release the seed. Once seed is mature, it will be released when conditions meet the plant's requirements. Some plants need excessive heat, others cold and still others need moisture or the lack of it to allow the seed to be released.
About the Author
Bonnie Grant began writing professionally in 1990. She has been published on various websites, specializing in garden-related instructional articles. Grant recently earned a Bachelor of Arts in business management with a hospitality focus from South Seattle Community College.