Puzzlegrass Grow On
Horsetail, scouring rush, or Equisetum spp.
Introduction
Horsetails are fairly common in wet ditches and considered a weed in people’s gardens. They spread through underground stems called “rhizomes” and can quickly take over an area. They have a single stem with short branch-like structures coming of it in whorls. There are stages in its lifecycle where the horsetail does, in fact, look somewhat like a horse’s tail. These plants belong to a group of plants that produce spores in order to reproduce and NOT seeds. Ferns and club mosses also belong to this group of plants. There are only 15 species of horsetail in the entire planet and at least three of them are found in Nova Scotia. Horsetails can grow in very poor soils, in either sunlight or shade.
Appearance and Habitat
Horsetails are a very unique plant. Young stages of some species can look like tiny evergreen trees. But otherwise, they look very different from most other plants. Horsetails are usually no more than 40 cm tall, usually shorter. The stems are hollow and appear jointed, and they can be stiff and feel rough to the touch. Although one species does not have whorls of branches leaving from the stem, the other two do. Most of the Nova Scotian species of horsetails have two separate plants that look quite different. In the early spring, they produce a whitish stem that is solely for reproductive purposes and holds “sporangia” that release the spores. These spores will eventually germinate and grow into new horsetails. After the fertile plant has released its spores, another green plant with branches emerges from the same rhizome. This plant will use the sun’s light to make energy for the plant for the rest of the growing season.
Relationships
Horsetails reproduce with spores, not seeds. They do not have pollen and eggs, and they do not have flowers. They do not need to be pollinated. The spores are light enough that they can be blown easily by the wind. They can also stick to animals and be moved to new places in that way. Horsetails are important in the ecosystem. They are one of the first plants to colonize newly disturbed soils. Their impressive underground root and rhizome system can help hold soils in place. There are some beaches in Nova Scotia (Pomquet Beach, Antigonish County, is one) where horsetails are an important part of the dune ecosystem and can be found growing among the dune grass. This is easily seen in the places where the dune is washing away. Horsetails are not commonly eaten by other animals (indigenous peoples often consumed them at certain phases) but bear and moose have been known to eat them. Horsetail roots also have an important relationship with mycorrhizal fungi in the soil. The fungi actually enter the cells where they provide the plant with hard-to-get nutrients. The horsetails give the mycorrhizal fungi plant sugars in exchange.
Human Use
The name “scouring rush” is used because this plant often produces silica crystals (essentially small pieces of sand) in its outer layer of cells. Because the silica crystals make the plant rough, they were commonly picked and utilized to clean pots and other dishes, just as we use scrubbies today. Horsetails have been employed for many different medicinal purposes over the years, including teas and poultices. Today some people include horsetail as a key ingredient in “all-natural” toothpastes.
Biomimicry
Scientists inspired by the unique abilities of certain organisms often try and create inventions based on those unique abilities: this is called biomimicry. Horsetails have little structures around their spores called “elaters”. The elaters are sensitive to the humidity in the air. When the humidity is low and the air is dry, they expand and catch more air, making the spores more buoyant so they can travel. When the humidity is low, the elaters curl up making the spore heavier and more likely to settle to the ground. This means that the spores are more likely to end up on the ground when the ground is moist. Spores need moisture to germinate and grow – so this is a good strategy. Inventors are trying to use this concept of humidity sensitivity to design a humidity control in greenhouses and special humidity sensitive packaging.
Scientific Name
Horsetails are known scientifically as Equisetum.
~Monica Schuegraf
