Living gymnosperms can be divided into four major groups: cycads, ginkgos, gnetophytes, and conifers. Although they have declined since the Mesozoic era, gymnosperms are still the dominant trees in some areas, especially at high elevations and latitudes. All gymnosperms are woody and have seeds that are not protected by ovaries, although some have fleshy, fruitlike cones or extensions of seeds that entice animals to disperse the seeds.
learning outcomes
You should be able to:
Describe and contrast the roles of male and female gametophytes in reproduction.
Summarize the functions of cones in conifers.
Describe the role of fire in the life history of the lodgepole pine.
How is fire necessary for the survival of some gymnosperms?
Some plants require fire for seeds to be released. For example, fire is needed to open the tightly closed cones and release the seeds of some pines, which are then able to germinate.
Distinguish between the roles of the megagametophyte and the pollen grain in the life cycle of a conifer.
The megagametophyte is the female gametophyte, or multicellular haploid tissue contained within the ovary of all seed plants. The pollen grain is the multicellular male gametophyte, which produces the sperm that fertilize the megagametophyte.
What is the function of the fleshy cones that surround the seeds of many gymnosperms?
These fleshy cones serve to attract animals, much as the fruits of flowering plants do. The animals eat the fleshy cones and the seeds they contain, and the seeds pass through the digestive tracts of the animals and are dispersed by their feces.
Although gymnosperms still dominate the terrestrial landscape in some environments, angiosperms (the flowering plants) have become the dominant land plants across much of the Earth.