It is no wonder that the many specie of horsetail have been around since the Carboniferous Age. They seem to be impossible to kill! Because they can be so invasive and persistent, they should be confined to planters or areas of the garden where they can be controlled. They should probably be kept away from thickly foliated areas where they can spread and mix with other plants unnoticed.

            Even though they are among the oldest plant specie, they seem well suited to modern architecture. Besides, the narrow areas between modern residences, walkways and driveways are confining by nature. Many modern buildings are even outfitted with awkwardly narrow planter areas that could use plants that get three or four feet tall without spreading out laterally, just as Equisetum hyemale, the most common species of horsetail does. The partial shade and potentially bad drainage in these confined spaces is not a problem.

            The hollow segmented stems are rich green with black or dark brown joints. Some specie of horsetail have symmetrical whorls of wiry stems radiating from their joints. Otherwise, no other foliage is evident. Small knobs on top of the stems produce rusty brown spores. The larger types of horsetail are more likely to become invasive. Equisetum scirpoides stays about half a foot tall and is relatively complaisant. I do not know the identity of the horsetail that I got this picture of; but it has unusually large spore ‘blooms’ and a more relaxed texture.