A non-flowering native plant, it appears very primitive and not attractive at all. Horsetail is rough to the touch. It produces erect stems that protrude from a rhizome. Fertile stems produce very characteristic leaves called microphylls that clasp the stem such that the stem appears leafless. Sterile stems produce characteristic needles that resemble pine needles so the plants look like small upright pine trees.
As a native of the Northern Hemisphere, it is not a non-native invasive weed, however it is damaging local ecosystems. Commonly found near rivers and streams, it tends to inhabit open, undisturbed land, typically agricultural livestock grazing pastures.
Similar to Japanese knotweed, Horsetail can spread using extensive rhizome networks and fragments of rhizome that regenerate to produce identical plants. However, Horsetail also spreads by sexual and asexual reproduction, through spore formation within small cones on the plant. These cone assist in spore wind dispersal, the spores then germinate under moist conditions.
Similar to Ragwort, Horsetail in toxic to livestock upon ingestion as it contains Pyrrolizidine Alkaloids and thiaminase, causing thiamine deficiency as well as Bovine Liver disease. Juvenile Horsetail is more toxic than mature plants, when such plants are harvested with hay and used as feed then many livestock ingest the toxic weed. Due to the rough nature of Horsetail, the spiny stems and leaves can in bed themselves in the eyes and mouths of livestock, damaging the skin and causing ulceration of eyes and mouth leading to infection and abcess formation.