Characteristics of Seedless Vascular Plants
Botanists group ferns, club mosses and horsetails together as being seedless vascular plants. A vascular system allows the movement of water and nutrients through the plant's body and, instead of reproducing with seeds, they reproduce asexually with spores. Most seedless vascular plants grow on land in moist areas.
The Vascular System
More than 90 per cent of the plants on earth are vascular plants, including all the familiar fruits, vegetable and flowers in our gardens, as well as ferns, club mosses and horsetails. Vascular plants have true roots and true leaves that take in water, minerals and other nutrients; they possess xylem or internal vascular tissues, which takes in nutrients from the soil, and phloem, which moves those nutrients throughout the plant. Non-vascular plants include true mosses and algae, which lack true leaves and true roots, and must take in nutrients in other ways.
Fruit, vegetables and flowers reproduce sexually; they require the male parts of the plant (pollen) to come in contact with the female parts of the plant (the ovary) for a seed to form. Ferns, horsetails and club mosses do not form seeds, but instead they produce spores like moss or fungi. In ferns, the spores form on the underside of the fronds inside a casing called the sporangia. Although the spores themselves are microscopic and often invisible to the naked eye, on many species you can easily see sporangia, which clump together in a formation called a sori. When the spores are released, they will lodge into the soil or other growing material and will form a tiny heart-shaped sprout called a prothallus. The prothallus contains antheridia, which makes sperm, and archegonia, which makes eggs. The prothallus must mature and then must be in contact with water for the sperm and egg to meet and fertilize. The embryo that is formed will grow into an adult fern; the prothallus will eventually disappear.
Since seedless vascular plants depend on the presence of water for their reproduction, many grow in damp conditions along creeks, near bogs or in low, moist forests. While many ferns, horsetails and club mosses prefer shady spots, some species thrive in higher light conditions. Many species of ferns can be incorporated into a garden setting, and particularly in rain gardens or native wildflower plantings. Since many ferns like low or indirect light, they can be useful for landscaping on the shady side of your house.
- Forest Preserve District of Cook County, Illinois
- "A Field Guide to Ferns and Their Related Families;" Boughton Cobb; 1974.