What are rushes?
There are 464 known species of Rush and 8 subspecies (genera) worldwide. Rushes are very slow growing. Most Rushes can be found in areas of poor-quality, moist soil, while the most well-known rush, the True rush (Juncus), grows only in wetlands.
Like grasses and sedges, the rush (Juncaceae) family is part of the enormous grouping of Flowering plants known as Angiosperms and so are frequently confused with each other as they often have very similar characteristics. An old saying that often helps differentiate them – although it is not totally reliable – is: “Sedges have edges, rushes are round and grasses are hollow right up from the ground!”
Sadly, accurately differentiating rushes from grasses and sedges can require a lot of professional analysis as rushes can come in many forms and display many of the same characteristics of both grasses and sedges.
Like grasses, rushes tend to form in either dense clumps or tufts. Rushes form three-sectioned capsules containing many seeds and tend to be more rigid in form than grasses and sedges and their stems are mostly round.
Rushes are what we call “Monocotyledons”, which means they have a single, embryonic first leaf that appears from a germinating seed. (See “Plant Latin” for a full explanation.) Their leaf structures vary from hollow leaves to small scales to leafless stems, depending on species, and they often have round stems and thick, long underground roots (rhizomes).
Rushes grow exclusively in wetland habitats. Like sedges, rushes are an important element in wetland food chains. They provide habitats for small invertebrates, which in turn provide food for other wildlife.
Once rushes dieback they provide food for many aquatic invertebrates. Rushes are grazed by small animals and their seeds consumed by waterfowl and small birds.
Rushes are slow-growing perennials (plants that complete their lifecycle in two years), although a few are annuals (plants that complete their lifecycle within one year).
Their numerous, almost inconspicuous flower heads can be arranged in a variety of forms (dense heads to loose clusters) depending on the species of rush and are usually produced at the end or side of a single erect stem.
Most rushes are bisexual and more rigid in form than grasses, so they are less adept at catching the pollen as it passes through the air.
Once pollinated, they form dry fruits made up of three-sectioned capsules containing many seeds.
The dried pith of rushes is used to make “Rushlight” candles and Soft rush (Juncus effuses) is used in Japan for Tatami matting, known worldwide for its hard-wearing abilities and an important industry.
The most commonly known rushes include: Heath Rush (Juncus squarrossus), Field wood-rush (Luzula campestris) and Hard rush (Juncus inflexus). Interestingly, the inappropriately named Bulrush (Typha latifolia/Schoenoplectus lacustris) and the Club-rush (Holoschoenus vulgaris) are sedges not rushes.
Rushes you are likely to come across are: Woodrush, Chestnut rush, Sharp rush, Baltic rush, Spiky rush.
References: United Nations Environment Programme (UNEP), Division of Technology, Industry and Economics; Botany for gardeners, Brian Capon, Third edition, Timber Press; Colour Identification Guide to the Grasses, Sedges, Rushes and Ferns of the British Isles and north-western Europe, Francis Rose, Viking, The Penguin Group; Royal Botanical Gardens, Kew, London; Missouri Botanical Garden; Latin for gardeners, Lorraine Harrison, Royal Horticultural Society; International Botanical Congress (IBC); Oxford English Dictionary, Oxford University Press.