I’ve been on the look out for two kinds of Equisetum over the last couple of days and have found both growing nearby. I often stroll the kids around the paved walkway that loops around the Courtenay Airpark and this is where I found both the Giant Horsetail (Equisetum telmatiea) and the Common Horsetail (Equisetum arvense) growing along the edge of the path.
Most of us are familiar with horsetails – their primitive appearance is distinctive and oddly compelling. Horsetails are ancient plants and date back to 300 million years when they were the size of trees. The horsetails of the Devonian and the Carboniferous periods belonged to a group called Calamites. They grew up to 18 meters tall and had trunks a half meter in diameter.
The horsetails that I found this week weren’t nearly as big but I found myself imagining how interesting it would be if they were.
Like the name suggests, Giant Horsetail (Equisetum telmatiea) is a large horsetail. The sterile stems of this plant can grow up to 3 m tall and 2 cm thick. I found the fertile stems which are shorter, growing up to 25 to 60 cm tall. The fertile stems are topped by a strobilus where spores are produced. Each joint of the stem has a sheath of reduced leaves. In E. telmatiea, the sheath is 2 to 5 cm long and has 20 to 30 teeth. Giant Horsetail can often be found in disturbed areas like ditches, gravel roadsides, and sandy lots as well as more natural habitat like moist forests and meadows.
The second horsetail that I found was Common Horsetail (Equisetum arvense). Like the Giant Horsetail, it was also producing fertile stems. However, E. arvense is smaller. The sterile stems are up to 60 cm in height, while the fertile stems grow to around 30 cm tall. The sheaths of the Common Horsetail are 15 – 20 mm long and have fewer teeth than the Giant Horsetail. I found these fertile stems growing alongside the path among gravel and rip-rap. Like Giant Horsetail, this species also prefers disturbed areas.
It’s amazing to think that these plants that are often missed have been successful in one way or another for over 300 million years. Puts human accomplishments into perspective!
For more information about horsetails, check out Jocie’s article Ancient Horsetails on Vancouver Island’s nature magazine Island Nature. John Wall has posted a great video of Giant Horsetail producing spores. There’s also an interesting post on Common Horsetails over at Willow House Chronicles that is worth a read.