Smooth Scouring Rush

Appearance

It is usually found in moist areas in sandy and gravelly substrates. It may be annual or perennial. It grows narrow green stems sometimes reaching heights exceeding 1.5 meters. The leaves at the nodes are small, scale-like brownish sheaths and there are occasionally small, spindly branches.

The sterile stem is green and usually has no branches, though short stubby branches may develop on some plants. The “leaves” are reduced to a sheath that surrounds the stem, with 10 to 32 black teeth around the top. The teeth fall off as the season progresses, leaving a thin dark ring around the top of the sheath.

The stem is firm, the central cavity mostly 12.7 mm to 20 mm the diameter of the stem.

Fertile stems are like sterile stems, but with a 12.7 mm to 25 mm long cone at the tip of the stem. Cones have a blunt tip or may have a tiny, inconspicuous sharp tip.

Aerial stems lasting less than a year, occasionally overwintering in the southwestern United States, usually unbranched, 20--150 cm; lines of stomates single; ridges 10--32. Sheaths green, elongate, 7--15 × 3--9 mm; teeth 10--32, articulate and usually shed early, leaving dark rim on sheath. Cone apex rounded to apiculate with blunt tip; spores green, spheric. 2 n =216.

Naming

Equisetum laevigatum A. Braun, Amer. J. Sci. Arts. 46: 87. 1844.
Equisetum funstonii A.A. Eaton
Equisetum kansanum J.H. Schaffner

Schaffner named this species Equisetum kansanum because he applied the name E. laevigatum to what we now know is the hybrid E. × ferrissii, a hybrid between Equisetum hyemale and E. laevigatum. The coarser-stemmed, occasionally persistent forms in the southwestern United States have been called Equisetum funstonii.

Habitat

Part shade, sun; sandy or gravelly soil; wet meadows, ditches.

Reproduction

By spores and rhizomes. Spore cones maturing in spring--early summer.