Scouring Rush

Abstract: The smooth scouring rush, Equisetum laevigatum, is the only species of Equisetum endemic to North America and thus should have a special place in the affections of American pteridologists. Unfortunately, however, there has been so much confusion concerning this species that most botanists, amateur and professional, are uncertain about whether they actually know it. As part of a recently completed monographic study of the genus Equisetum subgenus Hippochaete,1 I devoted special attention to this species, and wish to discuss the results of that study. In 1840, Nicholas Riehl collected a smooth-stemmed scouring rush along the banks of the Mississippi river below St. Louis, which Alexander Braun named E. laevigatum in 1844. A fruiting specimen of Riehl's collection is to be found in the New York Botanical Garden herbarium and another is in Vienna. George Engelmann, having seen Braun's manuscript apparently, went out along the Mississippi banks to collect this new species. The specimens he collected in August, 1843, have since been mistakenly considered the type. They are without cones and show the autumnal condition of the species, with colored sheaths reminiscent of those in E. hyemale. However, all have the internal structure as well as the smooth stems characteristic of E. laevigatum. In 1902, A. A. Eaton described a new Equisetum intermediate between E. hyemale and E. laevigatum, which he named E. hyemale var. intermedium. According to Eaton it had the external appearance of the former species and the internal structure of the latter species. He stated that Milde, certainly, and A. Braun, probably, based their descriptions of E. laevigatum partly on this plant. Eaton later (1903) described another new Equisetum of this alliance, E. funstonii.

Abstract: Disclosed is a Chinese medicine for treating flat wart, which comprises hemp seed 20g, white alum 10g, isatic root 15g, prepared nutgrass flatsedge rhizome 15g, scouring rush 15g, mirabilite 15g, and water 500 ml.

Abstract: The genus Equisetum is an ancient one, having possibly the longest fossil record of any extant genus of plants. There are about 20 living species' throughout the world, but the specific differences are often subtle and the species tend to run together. An example is E. moorei of Europe, also called E. hyemale var. schleicheri and E. intermedium (of Schur, not Rydberg), which is intermediate between E. hyemale and E. ramosissimum and seems to intergrade into both. Manton, 1950, showed cytological evidence of the hybrid nature of this European species, as well as of E. trachyodon and E. litorale, both of which had been previously suspected of being hybrids. She wrote: "The detection of three species hybrids among little more than a dozen representatives of the genus is a surprisingly large number, especially when the rarity of prothalli is remembered, and it suggests fairly clearly that speciation can still occur." In 1952, while attempting to identify the representatives of the genus Equisetum in northern Michigan, I became quite interested in the sect. Hippochaete, or scouring rush group, and have since adopted it as my doctoral thesis problem. Within this section there are several species that have been troublesome, including E. laevigatum. Part of this species was segregated into E. hyemale var. intermedium by A. A. Eaton, and called this because it was intermediate between E. hyemale and E. laevigatum. Schaffner later segregated those members of E. laevigatum with annual stems and blunt strobili as a new species, E. kansanum. Looking for additional characteristics by which to differentiate between these two species, I mounted their spores, and was greatly surprised to discover that all specimens from this area of Michigan that fit the description of E. laevigatum as 68

Abstract: he Horsetail (Equisetaceae) family comprises 30 species, all in the ancient genus Equisetum. During the Carboniferous age (more than 230 million years ago), the Horsetail family was the dominant plant group in the world, with plants reaching gigantic size. Two basic forms of horsetails survive today. One is the hollow, jointed, and leafless scouring rush. The other is the horsetail with whorls of slender, green, jointed branches around hollow, jointed stems, often occurring in great numbers, giving the appearance of a horse’s tail. Because the stems may become encrusted with minute particles of transparent silica, all of these plants often are named “scouring rushes.” The name arose from the use of these plants by the pioneers as a scouring agent for pots and pans. They also are reported to be equivalent to the finest grades of steel wool in polishing wood finishes and were formerly standard items with European cabinet makers. Several species of horsetail and scouring rush are found in the Pacific Northwest. They are perennial, non-flowering plants that reproduce by spores. The spore-producing portion (cone) of the plant contains thousands of dust-like spores equipped with spring-like appendages that uncoil as the spores dry,