Equisetaceae: Equisetum laevigatum
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Family Name
Equisetaceae
Common Name
Smooth horsetail
Description
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.
Horticulture Notes
Spore Collection: Collect fertile cones before spore release in early spring.
Germination: Spores require moist, shaded conditions for germination; vegetative reproduction via rhizomes is the primary method of spread. Spores produce small gametophyte plants in a couple of months. These plants generate sporophytes (spore producing) plants later in the year or in the following year.
Vegetative Propagation: Propagates readily through rhizome division and rooted stem cuttings.
Soils: Prefers wet to saturated soils, including silts, clays, and organic substrates.
Light: Tolerates full sun to partial shade, often grows in open wetlands.
Water: Requires consistently moist to saturated soils; tolerates periodic flooding.
Additional Notes
Native to the region, smooth horsetail has traditionally been used in herbal medicine for diuretic and wound healing. It contains high silica content and has been used historically for abrasive and cleansing purposes. The plant provides ground cover and habitat in wetland ecosystems. It can be invasive due to its rhizomatous growth.