Aquatic and Wetland Vascular Plants of the Northern Great Plains
1. Equisetaceae, the Horsetail Family
1. Equisetum L. -- Horsetail, scouring rush4. Equisetum laevigatum A. Br. -- Smooth scouring rush
Stems alike, mostly annual in our range, simple or with few irregular, erect branches, commonly branching from the base if the main stem is cut, erect, 3-9 dm tall, mostly 16- to 30-ridged, central cavity usually 2/3 to 3/4 the stem diameter; main stem sheaths longer than broad, 6-15 mm long, with a single dark apical band or the lower ones sometimes with a dark basal band as well, the teeth dark brown with scarious margins, free or partly connate in pairs, 1-4 mm long, deciduous and usually missing from most of the sheaths. Cones terminal on the main stem or on the main branches if branched from the base, pointed or blunt, sessile to short-stalked, eventually deciduous, appearing Jun--Jul. Wet meadows, seepage areas, stream banks, floodplains and ditches, also common in prairie and on embankments, often where sandy or gravelly; common; (Que. to B.C., s to WV, IL, TX and Baja CA). E. kansanum J. H. Schaffner.
A hybrid between E. hyemale and E. laevigatum is referred
to as E. X ferrissii Clute. The hybrid produces sterile cones with
abortive spores. Reproduction is entirely vegetative by rhizomes and fragmentation
of the stems. Sheaths and growth characteristics (e.g., semi-evergreen stems)
are intermediate between the parental species, although the absence of spores
is most diagnostic. The range of E. X ferrissii corresponds with that
of E. hyemale in the northern plains.
Previous Species -- Equisetum hyemale L. -- Common scouring rush
Return to Family -- Equisetaceae - The Horsetail Family
Next Species -- Equisetum palustre L. -- Marsh horsetail
