The plants pictured here were photographed in Red Rock Canyon State Park near Hinton, Oklahoma. They are of the species Equisetum hyemale in the Horsetail family Equisetaceae.
Scouring Rushes or Horsetails as they are sometimes known are an ancient species of plants related to the ferns. Like the ferns they do not produce seeds and reproduce by making spores. They have been doing this since the Carboniferous period some 300 million years ago.
The cylindrical stems of these plants are evergreen and consist of hollow joints or sections stacked up to produce unbranched stems 2 to 3 feet tall. The surface of these sections are ridged and a narrow black-green band or sheath of tiny leaves forms between each section.
The high silica content of these plants and the ridges on the sections make these plants useful for scrubbing or scouring, hence their common name.
They like sandy or loamy soils with plenty of moisture, they tolerate clay or limestone rich soils, and can be found along the margins of streams, rivers, ponds, and other habitats where their feet can stay wet. Their presence can, in certain drier areas, can indicate a natural spring or seep is nearby even when flowing water is not visible. While these plants were from Oklahoma, they occur in suitable habitats all over the U.S. and Canada. They are cultivated by gardners and escapees from cultivation have become pests in South Africa and Australia.