What are Gymnosperm Plants?
Although they are often unnoticed, people from all faces of the globe live around and encounter gymnosperm plants daily. What are gymnosperms? In botany, the term gymnosperm refers to a clade of non-flowering, non-fruiting, vascular seed plants. The word gymnosperm literally translates to 'naked seed'. There are four phyla that belong to the gymnosperm clade. Covered in this article are the characteristics of gymnosperms as well as a breakdown of their phyla and life cycles.
Characteristics of Gymnosperms:
- Lack flowers and fruits, but do have seeds.
- Gymnosperm plants appear to have evolved from spore-bearing plants called the progymnosperms.
- Gymnosperms contain secondary vascular tissues. This allows for the plant to increase girth as it matures.
- The majority of gymnosperms are evergreens. One deciduous gymnosperm is the Ginkgo biloba.
- Unlike seedless vascular plants, gymnosperms do not rely on water for fertilization. Instead of water, gymnosperms possess a partly developed microgametophyte (pollen grain) that is able to use the wind for dispersal/pollination.
- All gymnosperms exhibit cone like structures that contain the ovules. They sit partly exposed on scales of the cone. Since they are exposed before fertilization, this gives rise to the name 'naked seed'.
Although classified as a single group, gymnosperm plants are actually comprised of four different phyla. Here's a list and description of each phylum:
Phylum Coniferophyta -
- The phylum Coniferophyta is comprised of conifer, pine, fir, and spruce trees.
- Coniferophyta are the most numerous gymnosperms. They are also the tallest vascular plants with some coastal Redwood Pines reaching heights of over 300 feet.
- Pollen and ovulate cones appear on the same individual.
Phylum Cycadophyta -
- The phylum Cycadophyta grows mainly in tropical and sub-tropical regions. They have a distinct trunk with a few functional leaves atop. They are often mistaken for palms.
- The cycads are able to fix nitrogen into the soil due to a symbiotic relationship with cyanobacteria.
- Unlike the Coniferophyta, the pollen and ovulate cones of the Cycadophyta are located on separate individuals.
Phylum Ginkgophyta -
- The only living member of the phylum Ginkgophyta is the Maidenhair tree, better known as Ginkgo biloba.
- Like the cycads, pollen and ovulate cones appear on separate individuals.
- Unlike the other phyla of gymnosperm plants, Ginkgo biloba is a deciduous tree. Its leaves will turn yellow and fall off during the winter months.
Phylum Gnetophyta -
- This phlum is comprised of three genera and around 70 species of unusual gymnosperms. This phylum is more or less a collection of species that didnt' fit into the other phyla, but still are considered gymnosperms.
- Some species in this phylum contain a Strobilus structure that is similar to the flower cluster of angiosperms. The two are unrelated however.
Gymnosperms Life Cycle:
Gymnosperm reproduction varies across the four different phyla, but the production of the sporophyte and gametophyte remains very similar. To the right is a life cycle for Pine trees of the Phylum Coniferophyta. Clicking it will enlarge to full screen.
And with that, I'll conclude this basic overview of Gymnosperms. Please feel free to leave me any comments or constructive advice to better my article!
- Raven, Peter, George Johnson, Susan Singer, Jonathan Losos, and Kenneth Mason. Biology. 8th ed. New York: McGraw Hill, 2008. 593-96. Print.