The genus name of the dwarf horsetail (Equisetum scirpoides) combines the Latin words for horse (“equus”) and “bristle or animal hair” (“seta”). A miniature version of the Common Horsetail, it’s a perennial indigenous to America and northern Eurasia.
I. Appearance and Characteristics
Equisetum scirpoides (dwarf scouring rush or dwarf horsetail) Michx., Fl. Bor.-Amer. 2: 281 (1803). 2 n = 216. The smallest of the currently occurring representatives of the genus Equisetum (horsetail).
Equisetum, from the Latin, equus, “horse”, and seta, “bristle, animal hair”. Scirpoides, from the Latin, scirpus, “rush, bulrush”. Scouring Rush, a reference to its early use for cleaning pots, made possible by its high silica content. Other common names include dwarf horsetail, sedge horsetail, prele faux-scirpe (Qué), tradfräken (Swe), dvergsnelle (Nor), trad-padderok (Dan), hentokorte (Fin), dwergholpijp (NL), himedokusa (Jpn), skrzyp arktyczny (PL).
The smallest Equisetum, E. scirpoides has circumpolar distribution. Plants create compact and dense clumps, reaching a maximum height of about 30 cm. The assimilation and generative shoots are identical and grow together.
The leaves are reduced to a black sheath around the stem. The stems are green, unbranched, thick and about 1 mm with six ribs. The generative shoots with small cones dying after sowing the spores. The nodes occur at approximately 1 – 3 cm. The leaves are very small to about 1 mm, and arranged in around nodes. The corms are thin, yellow and brown.
The roots are very fine, black and densely surpassing the ground. Species grow best in the mud at the depth zone from 0 to 3 cm. Specimens reproduce primarily by vegetative division. Equisetum scirpoides is hardy and semi-evergreen. This species is quite a popular decorative plant seen in garden ponds, ornamental gardens and assumptions in nearly the whole world.
E. scirpoides was discovered and described by French botanist André Michaux. Detailed studies were conducted by the American botanist Oliver Atkins Farwell.
Identifiable as a horsetail by the upright, hollow, jointed, cylindrical stems with inconsequential and easily overlooked leaves. Distinguished from other horsetails by its low, slender, wiry, unbranched stems and its small size. This is the smallest living horsetail. Field marks, diminutive size, low, slender, wiry, unbranched stems.
Within Equisetum scirpoides there are two subspecies:
- Equisetum scirpoides ssp. scirpoides (A. Michaux, Fl. Bor.-Amer. 2: 281. 1803)
Hippochaete scirpoides (Michaux, Farwell) – Main subspecies, grows up to about 30 cm. Low, slender, wiry, unbranched stems. Stems erect or prostrate, hollow, segmented, rough surfaced, green. Internodes about 4 apart with segments marked by ashy grey bands. Sterile and fertile stems alike. Twisting and wiry in form, branching rare. Sheaths are tiny, 1 – 2.5 mm × 0.75 – 1.5 mm, with three teeth, dark with white margins. Cones usually 1 long with sharp pointed tips, borne on short stalks at the tips of fertile stems. Spores green, spheric. Rootstalk shiny black, creeping, freely branching, and wide spreading. Roots black to very dark brown.
- Equisetum scirpoides ssp. walkowiaki (R. J. Walkowiak, IEA Paper 2008)
Equisetum scirpoides (ssp.) minus (Lawson, Milde) – Smaller subspecies, grows up to about 15 cm. The botanical characteristics are identical with the main subspecies. Often seen primarily as an ornamental plant in Japan. Subspecies described by Scottish botanist George Lawson and eminent German botanist Carl August Julius Milde, but without a proper taxonomic name, which gave the Polish botanist Radosław Janusz Walkowiak (subsp. walkowiaki).
II. How to Grow and Care
Dwarf horsetail is a low-maintenance perennial suitable for a variety of garden settings. A key care point for dwarf horsetail is ensuring consistently moist soil, as it thrives in damp conditions akin to its natural boggy habitats. It’s also important to provide dwarf horsetail with partial to full shade, protecting it from the harsh afternoon sun which could lead to foliage scorch. Given its adaptability and minimal care requirements, dwarf horsetail is generally considered easy to care for, requiring just some attention to its moisture and light preferences.
Sunlight
Dwarf horsetail flourishes optimally under full sun conditions, which involve uninterrupted direct sunlight for at least 6 hours a day. The intensity of full sunlight promotes vigorous growth and enhances the plant’s health. Despite this preference, dwarf horsetail demonstrates a commendable degree of tolerance to partial sun, allowing some flexibility in planting locations. In suboptimal light, dwarf horsetails may display some physiological adjustments, like modified growth patterns, to maximize light absorption.
Outdoors, dwarf horsetail should be positioned in areas where it can receive abundant light for the better part of the day, though it can also cope with light dappled by the intermittent shade of nearby plants or structures.
Watering
Originating from moist, shady environments, dwarf horsetail thrives in conditions that mimic its native habitat’s high humidity. This species exhibits a strong preference for consistent moisture and is relatively intolerant to drought. For optimal health, dwarf horsetail should be watered twice a week to maintain the soil’s dampness without causing waterlogging. As an evergreen plant, dwarf horsetail retains its foliage year-round, requiring careful attention to watering even during the cooler months when indoor heating can reduce ambient humidity.
Soil
Dwarf horsetail performs best in full sun or part shade in fertile, moist to wet soils. While it thrives in consistently moist garden soil.
Fertilizing
For dwarf horsetail, employ balanced nutrition fertilizers to promote robust growth and stabilize its unique reed-like structure. Fertilize biannually, in spring and mid-summer, with a half-strength liquid fertilizer, ensuring not to exceed the recommended label dosage to avoid root burn. The nutrient uptake of dwarf horsetail fluctuates with seasons; lighter feeding during active growth aligns with its metabolic needs. Always water dwarf horsetail post-fertilization to assist in nutrient distribution. During dormancy in colder months, cease fertilization to match dwarf horsetail’s rest period. Novice gardeners should wear gloves to prevent skin irritation when administering fertilizer.
Propagation
This species, part of the ancient fern allies, thrives in moist environments, favoring riparian zones. Propagation typically involves dividing its rhizomes or utilizing spores, although the latter is less common in a casual gardening context. When dividing rhizomes, gardeners should ensure each section contains at least one growth node, as this is where new shoots will emerge from. Cut rhizome pieces should be planted immediately in moist soil, maintaining high humidity to encourage root development. Careful handling of the delicate crowns during transplantation maximizes the success rate of new growth in dwarf horsetail.
Transplanting
The optimal timing to transplant dwarf horsetail spans from when frost recedes to the warmth of late spring, again resuming in the gentle embrace of early autumn. Site dwarf horsetail in a moist, shaded location for a seamless transition. Gentle encouragement aids root establishment.
Repotting
Repot dwarf horsetail every 2-3 years to accommodate its creeping growth habit as a ground cover. Best done in early spring, this timing aligns with its active growth phase. Opt for a wide, shallow container, as dwarf horsetail prefers spreading laterally. Post-repotting, ensure consistent moisture and avoid deep shade for robust recovery. These steps will maintain dwarf horsetail’s compact elegance and rich green coloring.
III. Uses and Benefits
Perfect for rain or water gardens, the clumping dwarf horsetail provides ornamentation when grown at the edge of ponds or bogs or in the wet soil in shady garden borders. It also grows well in containers placed in moist outdoor locations. The evergreen foliage provides ornamentation all year long, and the stems are resistant to deer.
