Scouring Rush

• By
• Richard Hebda

On the coast, scouring rushes are most evident in the winter when the deciduous leaves of surrounding plants have fallen.

Tall, evergreen, bamboo-like shoots stand in masses, often among shrub stems. Scouring rush shoots arise from a vigorous underground rhizome (root-stem) system, parts of which occur near the surface and other portions of which may be metres deep in the soil. These firm black structures bear numerous short rootlets at the nodes. The hollow, unbranched stalks stand stiffly, reaching 20 to 150 cm (8 to 60 in.) tall or more, but bend easily between widely separated nodes. The surface is covered in rough vertical ridges, distributed between the firm nodes that partition the inside of the stalk. At the nodes are all that you see as leaves, for they have become fused into a blackish band, at the top of which are the tiny tooth-like leaf tips. Scouring rush is a primitive plant, that is, it has no flowers and does not reproduce by seeds. Rather, like ferns, it reproduces by spores that are formed in sacs grouped into tiny soft cones at the tops of the stalks. The spores spread by air and if they land on a moist surface, they develop into inconspicuous plantlets where male sperm swim from the male reproductive structures to fertilize eggs from which a mature plant develops. Scouring rush occurs throughout B.C., even in the cold northlands. Globally it ranges around the Northern Hemisphere as far south as California and Florida in North America.

The habitat includes moist sites such as stream banks, flood plains and wetlands from lowland to mid elevations. It often favours partial to full summer shade, though in the interior it thrives on sandbars in full sun. Scouring rush colonizes roadsides, railway embankments and old fields, too. On the B.C. coast, you may encounter another very tall (to 3 m/9 ft.) evergreen specimen, giant horsetail (Equisetum telmateia), which bears branches at the nodes. This evergreen perennial is best propagated from rhizome divisions removed from the soil with at least one stalk attached. It may also be available in pots from nurseries specializing in wetland and aquatic plants. Scouring rush is best used as a potted accent subject or pond and wetland plant, also contained in a pot. Scouring rush rhizomes have the ability to spread, though not as invasively as those of common horsetail. If you have a large pond, then you can let it roam freely, especially among shrubs. Transplanted clumps may take a year or two to become established. Almost any moist soil will suffice, but a somewhat loose, gritty, moist soil with abundant organic matter is probably best. As the common name suggests, the stalks are rough, because they contain silica. First Nations people used the stalks to polish (sand) wooden objects such as canoes, dishes and arrow shafts.

Some used the rhizomes to decorate woven baskets. You can use the stalks when camping in the bush to scour out your frying pan and pots. Scouring rushes have been around for a long time, since the Paleozoic more than 350 million years ago. Some experts claim that Equisetum is the world's oldest surviving genus. Gigantic woody relatives of our scouring rush formed forest stands up to 20 m (66 ft.) tall, and their fossils are well-known the world over. Honour our ancient primitive plants with a pot of scouring rush in your garden. It provides a fascinating, simple, structural form to use in moist, dull corners of the garden. The following plants are hardy to the zone number indicated: • Equisetum arvense (common horsetail) - zone 3 • Equisetum hyemale (scouring rush) - zone 3 • Equisetum telmateia (giant horsetail) - zone 6 An expert on native plants, Richard Hebda is curator of Botany and Earth History at the Royal British Columbia Museum in Victoria