Introduction
Horsetails are on the branch of the plant tree of life that includes whisk ferns, and ferns. The other members of this clade are examined in Lab #7.
Raven 8th p. 419-427, Raven 7th, p. 399-405
The Equisetaceae (horsetails) was a dominant and diverse group of plants about 400 million years ago, in the Paleozoic era. Today, however, this group consists of a single extant genus, Equisetum. They are worldwide in distribution, including Australia and New Zealand. They grow in wet habitats, but are able to survive in dryer places at least for part of the year. They can be a serious problem to livestock due to thiaminase in their stems. Thiaminase destroys thiamine and results in a vitamin B1 deficiency, causing serious poisoning. However, preparations have been used medicinally by a number of different cultures.
Use the links below to learn more about the horsetails:
GENUS
STEM and LEAVES
STROBILUS