Title: Grasses, Sedges and Rushes - an introduction

In the mosaic of habitats that dot our landscapes, grasslands stand out as vibrant ecosystems often teeming with life. The prevailing natural conditions, soil acidity, dampness, agricultural uses. etc make for a diverse array of grassland habitat and, significantly, the species of grasses, rushes and sedges that might be found. Some grasses are tolerant of most conditions whilst others are more specialised; quaking grass, for example, is confined to calcareous soils whereas purple moor grass is very much at home on more acid soils. 

Many grass species prefer drier soil conditions but some are quite at home with their roots in water. Also in watery realms sedges and rushes play integral roles. Despite their often subtle appearance, these groups of plants form the backbone of wetland habitats, providing structure, stability, and sustenance to a diverse array of wildlife. 

These plants also contribute to nutrient cycling and carbon sequestration, capturing carbon dioxide from the atmosphere and storing it in their tissues and in the soil. As primary producers, they form the base of the food chain, providing sustenance for herbivores and serving as a critical link between aquatic and terrestrial ecosystems.

Grasses:

Grasses, belonging to the family Poaceae, are ubiquitous components of all grassy landscapes, meadows, downland, grazing marshes and riverbanks with their slender blades and intricate inflorescences. While many grass species are associated with dry habitats, a significant number have adapted to thrive in wetlands, where they play essential roles in stabilising soils, filtering water, and providing habitat for wildlife.

Grasses are characterised by their hollow stems, parallel-veined leaves, and fibrous root systems, which help anchor them in muddy or saturated soils. Despite their modest appearance, grasses exhibit remarkable diversity, with species ranging from delicate tufts of hairgrass to towering stands of pampas grass.

The Sidmouth Nature project discovered some thirty species of grass in the first two years, there may be a few more species still to be found.  Some species such as sweet vernal grass, cocksfoot, Yorkshire fog, false oat grass, annual meadow grass and perennial ryegrass are widespread and found on most of the survey sites in varying degrees of abundance. Others are more restricted with crested dog's tail and timothy found on some dry grassland, barren brome and soft brome common in hedgerows and scrub whilst woodland reveals rough meadow grass and wood millet. 

Sedges:

Sedges, members of the family Cyperaceae, are often found alongside grasses in wetland habitats, where they contribute to the structural diversity and ecological complexity of these ecosystems. Unlike grasses, sedges have solid, triangular stems and leaves arranged in three ranks, giving them a distinctive appearance that sets them apart.

Sedges are particularly well-adapted to wetland environments, with many species possessing specialised adaptations for growing in waterlogged soils or shallow water. Some sedges, known as tussock sedges, form dense clumps or tussocks that provide refuge for small animals and nesting sites for birds.

The lack of true wet grassland means sedges are more restricted in their distribution in the Sidmouth Nature project survey area. By far the most common is pendulous sedge and this tall, robust, invasive that is often grown in gardens  has found its way on to many of the survey sites.  Woodland sites frequently have wood sedge, some in abundance, and the damp areas of the heath habitat on Muttermoor has occasional green-ribbed sedge plants.

Rushes:

Rushes, belonging to the family Juncaceae, are another common sight in wetlands, where they thrive in a variety of aquatic and semi-aquatic habitats. Unlike grasses and sedges, rushes have round, solid stems and simple, linear leaves, giving them a distinct appearance that distinguishes them from other wetland plants.

Rushes are often found in marshes, bogs, and along the edges of streams and ponds, where they help stabilise shorelines, reduce erosion, and provide habitat for a variety of wetland species. Some rushes, such as the common reedmace (sometimes known as the bulrush), produce distinctive seed heads that add visual interest to wetland landscapes.

As an easy guide to deciding on whether a plant is a sedge or a rush, remember: “Sedges have edges whilst rushes are round.”

As with sedges, rushes are restricted to a few damper areas where soft rush and compact rush are the most dominant species. The heath on Muttersmoor had heath rush, toad rush, sharp-flowered rush, bulbous rush and heat woodrush. Damper, short turf elsewhere will occasionally be home for field woodrush whilst damp woodland will reveal occasional great woodrush.