Equisetum laevigatum is a rush-like perennial that rises from an underground rootstock structure. Normally the plant dies back over the winter, but some populations in the southwestern USA have individuals that can overwinter. The plant manifests jointed rough stems which are closed at the joints. The stem roughness are a result of inclusions of silica. Each stem exhibits longitudinal grooves that run vertically. Each joint has a sheath which is a minute pointed leaf-like structure. The species usually occurs along moist drainages in sandy and gravelly substrates.
The narrow green stems can attain heights ranging from 30 to 150 centimeters. The stems are generally unbranched and are capped with rounded cone-shaped sporangia. Stomata occur in single lines; moreover, the spherical spores of this species are green.
The appearance of this taxon is very similar to E. hyemale; moreover, The geometric arrangement of silica-tuberles at the shoot surface may be the best means to differentiate these two species.
- *Jepson Manual. 1993. Equisetum laevigatum. University of California, Berkeley, Ca
- *Flora of North America @ eFloras.org http://www.efloras.org/florataxon.aspx?flora_id=1&taxon
Equisetum laevigatum is looking much similar to E. hyemale, thus is nearby impossible to identify by images. The arrangement of silica-tuberles at shoot-surface is best feature to separate these spp. They are arranged in +- irregular rows transversely to shoot-axis or to some angle, more rounded and sometimes confluent in rows at E. laevigatum (as in E. ramosissimum). E. hyemale got silica tuberles quite strict in 2 rows along the ridges (ex my memory). If i do remember right, E. laevigatum does lose its sheat-teeth readily, whereas E. hyemale ssp. affine tends to keep them. Colour of shoots for usual is different, more light green to somewhat yellowish in E. laevigatum, and dark green in E. hyemale, whose shoots may grow thicker and higher, but this feature is very variable, depending on clones and habitats (own experience).