Giant horsetail is an annual herb with dimorphic stems. Separate fertile and sterile or vegetative stems are joined together by underground rhizomes.
The greenish-to-brown sterile stems lack cones and have fine, jointed, and descending branches developing in whorls from the nodes between stem segments. They grow to 3 m tall and 2 cm thick. The perennial rhizomes have adventitious roots arising at the nodes. The rhizomes are black, covered in felt-like hairs, and may have pear-shaped tubers at the joints.
Giant horsetail is the largest of the common horsetails, explaining its common name. Giant horsetail is found at low to middle elevations usually near standing or flowing water. Dense colonies often form in moist forests and meadows, stream banks, swamps, seepage areas, and gullies, giving the landscape a prehistoric look.
This species is found in the pacific northwest from Alaska to southern California. On the Pacific Coast, including all of Vancouver Island.
This species was the most preferred Horsetail species of coastal first peoples as an important springtime vegetable. The young fertile and vegetative shoots were picked, de-sheathed, and eaten raw. Some first peoples also picked the tops of these plants, boiled them, and drank a glassful of the liquid to cure a urinary ailment.
The silicon dioxide crystals make Giant Horsetails great scouring tools. Native peoples used them extensively for smoothing and polishing wood and soapstone. In fact, modern-day hunters and outdoors people still use them as scouring utensils for cleaning pots and pans.