Equisetaceae: Equisetum laevigatum

Equisetum laevigatum is a perennial, herbaceous vascular plant reproducing primarily via an extensive system of underground rhizomes, allowing vigorous asexual spread. The plant produces green, hollow, jointed, and unbranched sterile stems that are smooth (hence “laevigatum”), typically 30–90 cm tall, with silica deposits giving them a rough texture to the touch. Fertile stems, which are separate, arise in early spring and bear sporangia in cone-like strobili at their tips. Leaves are reduced to small, fused sheaths at stem nodes, and true leaves are absent. Smooth horsetail does not flower but reproduces sexually by spores, produced in fertile cones during early spring. Sterile shoots emerge after the fertile ones and photosynthesize throughout the growing season. Smooth horsetail is native to South Dakota, inhabiting moist to wet areas such as riverbanks, floodplains, wet meadows, and ditches, with distribution statewide, especially in eastern and central regions.