Members of the Horsetail family are delicate, pretty, ecologically important – and potentially harmful to people and animals.
Lunch for Bears
There are nine Horsetail family species here, but the one you’ll most likely see is the Common Horsetail. Another member of the Horsetail family, and reasonably indistinguishable from Common Horsetails, are the Scouring-Rushes. The way to tell the various species apart is to look at the stem joints, which are all different.
Research on bear diets clearly shows that an early season food source are the new, fresh shoots of the Horsetail family of plants, pictured above right. To a bear, all members of the Horsetail family are just good eats.
Often mistaken for ferns, Horsetails look more like miniature trees, and are not frilly. They tend to grow in wetter places, and sometimes grow in great carpets. When full grown in mid-June, these create a rather magical, elfin-feel to the forest. The most famous in K-Country is the mis-named “Fern Forest” west of Canmore. The Terrace Trail just north of Galatea also hosts a pretty Horsetail forest. Horsetails can get up to 30 cm tall, and are delicate and soft. Bears only eat Horsetails in the spring when they are young and fresh shoots, much as humans eat fiddleheads, which are the immature shoots of ferns.
Pretty but sometimes deadly
Part of the reason that bears do not touch Horsetails after early June is the plant has an unusual attribute: it pulls silica out of the soil. As it grows, it becomes more and more made of silica. When it dies in the fall, it turns white because the silica is almost all that is left, pictured at right and at the top of this page. That silica is so sharp and coarse, it can actually cut holes in the digestive tract of anything that eats it. This is how some plants in the family got the name “Scouring-Rush”; in mid- to late-summer, they were used as scouring pads to clean pots by western pioneers, and even used as sandpaper. Indigenous people used them to polish arrows, bows and pipes.
We, too, can be like bears and eat the young shoots, but must be careful. They contain an enzyme called Thiaminase that destroys vitamin B1. While it has no effect on bears and the many other wild animals that eat Horsetails, it can kill cattle and sheep that eat it. If eaten raw, it can very severely affect people, especially those with high blood pressure. Horsetails must be cooked to destroy the Thiaminase.
Read about other plants in K-Country here!