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Parts of a Horsetail

Horsetail, or Equisetum, is a plant descended from a very ancient plant. It is part of a family of plants that was here before flowering plants. The horsetail first appeared during the Carboniferous period, about 360 million years ago. Modern horsetails are much smaller than their ancient ancestors but basically unchanged, and are found all over the world.

Species
- There are several species of horsetail including the dwarf horsetail which grows in cool forests. The giant horsetail grows near streams and swamps and can be up to 6 feet tall. The rough horsetail is found in wet gravel or sand along streams and can grow to 5 feet tall. The smooth horsetail's range is restricted to the United States. The field horsetail is the most common horsetail in North America, the wood horsetail is found in forests all over the world and the water horsetail is found in swamps, ponds and ditches. Most are poisonous to livestock.
Stems
- Horsetail has ridged and segmented stems. With the dwarf horsetail, silica deposits on the ridges and makes them rough.The rough horsetail accumulates so much silica that it's used for scouring. The giant horsetail has two types of stems. One is brown and fertile and is from 1 to 2 feet tall. This stem sheds its spores in spring and then dies, to be followed by stems that are sterile, hollow and up to 6 feet tall. The stems of the field horsetail are also green and hollow, but pink fertile stems come in the spring. The stems of the water horsetail are flat and have very little silica, thus are very smooth.
Branches and Roots
- The branches of most horsetails grow in whorls from nodes around the stem, and are very thin and filament like. The wood horsetail is the only horsetail with compound branches. They are quite lacy and droop attractively downward. By contrast, the branches of the marsh horsetail reach upwards. The stems of the smooth and rough horsetail have no branches at all. The horsetail reproduces both by spores and a deep, creeping rhizome system.
Leaves and Cones
- Horsetails reproduce through spores and rhizomes.
  
  The leaves of most horsetails are tiny scales fused into sheaths from 2 to 12 mm long. The cones, or strobili, are borne on the tips of fertile stems, most of which lack branches. The wood horsetail is the exception in that the fertile stem has branches as well as the non-fertile stem, and in the marsh horsetail the stem might be fertile or sterile. The cones of the different species can be different, with some being sharp and pointed and others being blunt.

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