The name gymnosperm comes from a Greek word that means naked seeds. They are so named because the seeds are not enclosed in an ovary and instead are on the surface.
Gymnosperms are plants that produce cones and seeds instead of flowers. Pine, spruce, fir, and ginkgos are all examples of gymnosperms. They often grow in temperate and boreal forests in wet or dry climates.
Gymnosperms are the Oldest Type of Plant
Gymnosperms date back to the Paleozoic era where they were an abundant plant. Today, there are about 700 to 900 living species. They are thought to be the first vascular plants on lade, and they first appeared about 245 million years ago.
A plant’s vascular system allows water to move from the root to the rest of the plant. Without it, plants can not survive on land. However, the gymnosperm is thought to be the first vascular plant, and thus the first plant that could survive on land.
How Gymnosperms are Different From Other Plants
Plants that produce flowers or fruits are called angiosperms. Unlike gymnosperms, angiosperms have seeds that are surrounded by an ovary. In a fruit tree, the fruit is the ovary, and the seeds are located inside the ovary.
Gymnosperms, by contrast, do not have an ovary around the seed. The seeds are not enclosed and instead are on the surface of leaves or on cones. They look like scales on the outside of a cone.
One key difference between the two types of plants is that angiosperms are seasonal, and they die or are dormant in the winter. Gymnosperms, however, are evergreen and do not lose their leaves or die in the winter.
Angiosperms can be either unisexual or bisexual, but gymnosperms are unisexual. Angiosperms rely on pollinators like bees and other insects for reproduction, but gymnosperms rely on the wind for reproduction.
Gymnosperms Come From a Group Called Seed Plants
Gymnosperms are in a group of plants called seed plants, also called spermatophytes. Before seeds, plants could not grow in a dry world. When plants evolved to have seeds, vascular plants could then drop seeds on land, which allowed them to spread across the Earth.
A seed has three parts: the embryo, the coating of the seed, and a food source. A fertilized egg forms into an embryo in the seed. The embryo forms its first leaf and begins to develop a root and stem while still inside the seed.
The coating of the seed is tough and protects the embryo. It prevents the embryo from drying out until the embryo can begin germination.
The embryo needs energy in the seed, and the seed can also store this energy in the endosperm. It gives the embryo energy to survive until the embryo can begin making its own food.
There are Two Types of Gymnosperms: Conifers and Cycads
There are two main types of gymnosperms. Today, there are over 700 different species of conifers. These are mainly pine trees, and they have a leaf shaped like a needle. They often take over their habitats and spread quickly. They are often used for paper or wood.
Conifers are evergreen trees. They do not lose their leaves, or needles, in the winter. They use their needles to protect them from the cold weather and the dry conditions in the winter.
There are about 300 different species of cycads. These have leaves that look like ferns, and the trees usually have stout trunks. They are found in tropical climates. They have bright cones that contain seeds, and the bright color attracts animals to pollinate them.
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What is the Life Cycle of a Gymnosperm?
Gymnosperms have evolved in the last few million years, and each of the groups has a slightly different life cycle. For this unit study, we will focus on the life cycle of a conifer.
The sporophyte phase is the spore-bearing phase. This is the adult plant that produces either pollen cones, also called male cones, and ovulate cones, or female cones. Pollen cones are usually smaller than ovulate cones.
The male and female cones can be produced by the same plant or by different plants. When they are produced by the same plant, the female cones are found on the upper part of the branches on the tree, and the male cones are in the bottom branches.
During the gametophyte phase, the male cones produce sperm, and the female cones produce egg cells. The female cone will stay attached to the plant until it is fertilized and the seeds start to disperse.
For gymnosperms, much of the pollination is due to wind or other natural means. The pollen that contains the sperm cells is carried to the female cones either by wind or by insects that fly from cone to cone.
Once the pollen is carried to the female cone, the female cone closes for a long time, sometimes until the following year. During that time, the pollen germinates and creates pollen tubes. These pollen tubes take almost a year to deliver the sperm cells to the egg cells.
When the sperm meets the egg, it forms a sporophyte that is surrounded by a seed. These seeds are found on the cones and look like small scales. Eventually, these scales will separate from the cone. The wind will carry them, and they will land in the ground and germinate and develop into a new plant.
The Benefits of Gymnosperms to Humans
Humans have many uses for gymnosperms, even though they do not produce fruit or flowers. Here are some of the uses:
- Humans use these plants for food sources, including for starches, eating the leaves, and to make wine and other food.
- Some gymnosperm species are used to make medications.
- The bark of trees from the Taxus genus of gymnosperms is used to make the anticancer medication taxol.
- Some species of the Cycas plants are used to make hair care products.
- Oils extracted from some species are used for perfumes, air fresheners, and other fragrances.
- Some plants are used as decorations in gardens.
- The wood is often used to make paper.
- Leaves from some species are used to make eco-friendly household products.