Field horsetail (Equisetum arvense) is a representative of the sporangiophores plants. All existing today horsetail plants are united in a single genus - Equisetum, numbering about 20 species. The modern horsetails are of modest size and are perennial herbaceous plants. In contrast, in the distant geological past in its peak period many of the horsetail species were real trees raising majestically their succulent-textured sporangia stems and branches up to twenty meters high. They formed forests covering large areas. Later, their fossils have turned into coal.
Field horsetail is a type of perennial plant with branched underground rhizome of up to 50 cm deep in the ground. Rhizome is composed of nodes and internodes. The side branches of roots mutate into rounded tubers, which accumulate nutrients (mainly starch), succeeding the vegetative propagation. The Horsetail reproduces through fertile spore-bearing parts located on top of the spring stem.
Field horsetail develops each year two types of underground stems - spring and summer ones. Already in early spring (hence their name spring stems) the stems grow up quite faint at first as later they turn to to dark brown stems, on top of which is located the strobilus. After maturation these fertile stems wilt fast. Not long after, from the same rhizome grow numerous green and jointed stems. Although they appear at the end of spring, they are called summer stems. They do not form strobilus and therefore bear the name vegetative or sterile stems. Their main role is to photosynthesize.
After the removal of the over ground parts, the Field horsetail grows back from the deep underground rhizomatous stem system. The rhizomes are bold stem parts that grow above or below ground. They easily build roots and form new plants.
The name in Bulgarian for Horsetail „hvosht“ comes from a Slavic word, which means „tail“. The scientific name for the genus – Equisetum is of similar origin. It is derived from the Latin word "equus" - horse "saeta" - hair, mane.
In Bulgaria can be found 7 species from the Equisetaceae Family as well as their hybrids, all sharing a very similar appearance. Field horsetail and most other species of horsetail are widespread and very common in the Bulgarian territory. The only exceptions make the forest and marsh horsetail, which are rare.
In Bulgaria Field horsetail occurs in moist and shady places along the rivers, in meadows, marshes and along embankments in foothill areas with an altitude of 1600 m. The Field horsetail is an important habitat for aquatic invertebrates and some aquatic birds and mammals use it for food. Furthermore, the species has an important implication as a medicinal plant.