Do all plants grow from seeds?
No, there are actually a few plants that do not make seeds. Whether or not a plant makes seeds is one criteria used to classify plants. How else could you distinguish between plants?
Plants are formally divided into 12 phyla (plural for phylum), and these phyla are gathered into four groups (Figure below). These four groups are based on the evolutionary history of significant features in plants:
- Nonvascular plants evolved first. They are distinct from the algae because they keep the embryo inside of the reproductive structure after fertilization. These plants do not have vascular tissue, xylem or phloem, to transport nutrients, water, and food. Examples include mosses, liverworts, and hornworts. Without vascular tissue, these plants do not grow very tall.
- Seedless vascular plants evolved to have vascular tissue after the nonvascular plants but do not have seeds. Examples include the ferns, whisk ferns, club mosses, and horsetails. Vascular tissue allowed these plants to grow taller.
- Gymnosperms evolved to have seeds but do not have flowers. Examples of gymnosperms include the Redwood, Fir, and Cypress trees. Gymnos means "naked" in Greek; the seeds of gymnosperms are naked, not protected by flowers.
- Flowering plants, or angiosperms, evolved to have vascular tissue, seeds, and flowers. Examples of angiosperms include magnolia trees, roses, tulips, and tomatoes.
- Nonvascular plants were the first plants to evolve and do not have vascular tissue.
- Seedless vascular plants have vascular tissue but do not have seeds.
- Gymnosperms have seeds but do not have flowers.
- Angiosperms have vascular tissue, seeds, and flowers.
Use the resource below to answer the questions that follow.
- Plant Body Systems and Classification Part 1 at http://www.youtube.com/watch?v=6FnPVFPSt3A (7:21)
- What plant groups are included in non-vascular plants
- Give an example of a seedless vascular plant.
- What groups of plants have seeds?
- What groups of plants have fruit?
- Where do you usually find non-vascular plants? Why?
- What distinguishes the gymnosperms from other plants?
- What were the first types of plants to evolve?
- List the following major features of plants in the order they evolved: seeds, vascular tissue, flowers.
- Give two examples of seedless vascular plants.
- Give two examples of angiosperms.