07-Aug Whispering Blades: The Secret World of Grasses & Sedges

The smallest grasses we see a lot of tend to be the bents Agrostis spp. The word bent is believed to mean coarse grass which could well explain the bent in Bentley Priory Open Space in Harrow which, as already mentioned, is another good place to look for grasses.

They are attractive, fine, tufted or creeping grasses. Their tiny flowers (spikelets) are set in whorls, usually awnless and often glossy. There are three common species in London of Which Fiorin or Creeping Bent Agrostis stolonifera is probably the most ubiquitous.

This can be recognised sometimes by its long leafy runners and stems that are often bent at their base. It can be found in all types of grassland and some dwarf forms are even added to lawn mixtures. Common Bent A. tenuis is equally common and often on poor soils such as heaths where it can form a continuous turf. Black Bent A. gigantea is the most robust of the three with stout erect stems, large flowerheads and rough leaves. It is also taller (150 cms.) and found on both waste and cultivated ground. A fourth bent, Velvet bent A. canina is less common. It has fine bristle-like leaves, awns that the others don’t possess and prefers wetter places such as marshes and wet woods.

An attractive grass that truly belongs to August is Purple Moor Grass Molinia purpurea as it only starts to flower this month. It forms elegant eye-catching tussocks with wide sprays of flowerheads on damp heaths. Not only this but its leaves turn an attractive colour in the autumn but are probably best seen in winter when covered in dew or frost in places such as Richmond Park. Being so architectural it is small wonder a variety of its cultivars are popular in London gardens. The Common reed Phragmites communis is another grass which is only just coming into flower now but will be very noticeable for the next three months. This is one of the largest grasses we see in London (3 metres) excluding the enormous Pampas Grass and bamboos that we see in gardens.

It has silvery purple flowerheads that all wave in the wind in unison in the reedbeds it creates. These are especially abundant in the tidal marshes along the lower Thames. It provides the reeds used to thatch roofs but was also used to make screens and furniture and even a liver cure. Saltmarshes and saltings generally have their own saltmarsh grasses that are generally erect sturdy species of Rice grass (Spartina) or Saltmarsh grass (Puccinellia).

Where the former species is found dominating the marsh, as it often does, there is occasionally a slight smell of rotten eggs. Other rarer grasses worth looking out for this month include Common millet Panicum miliaceun, Canary grass Phalaris canariensis, Bristle-grasses Setaria spp., Bermuda grass Cynedon dactylon and Rye Secale cereale in places such as roadsides and rubbish dumps.

Most of the sedges tend to go unnoticed or get missed due to their lack of conspicuous features and to some extent their choice of habitat. Largely they like wet conditions and so are best looked for in marshes, wet woods, boggy areas and at the edges of ponds, lakes and rivers. Crofton heath in Bromley might be a good place to start, boasting fourteen different species and the impressive stands of sedges on Rainham marshes, Ravensbourne meadows and Fray’s farm meadows may be worth visiting for further inspiration.

The sedges in our gardens are much more impressive as the cultivars of collected Japanese and American sedges tend to be much more colourful. We do have one popular native cultivar which is often seen. This is Bowles Golden sedge Carex elata ‘Aurea’ discovered by E. A. Bowles, the “Crocus King” of Enfield on a holiday in Norfolk. However, there are some late-flowering native sedges also worth looking out for.

The False Fox sedge Carex otrubae is common and can form tufts up to a metre high. It has the typical congested tips of spiky flowers of so many other Carex species. The Lesser Pond sedge C. acutiformis is similar to the Great Pond sedge C. riparia already mentioned but with narrower leaves that taper to a sharp point. The two often grow together but should be handled with care as their saw-like leaves are quite capable of inflicting a painful cut. The Grey sedge C. divulsa differs in that it is more likely to be seen along a woodland ride. Its flowers are much more separated along its stems than other sedges. The Thin-spiked Wood sedge C. strigosa is also found in woods and is similar to the Wood sedge C. sylvatica but with much broader pleated leaves. It is not common nor easy to find, sometimes showing a preference to be near springs in woods which woodland paths never seem to lead to. A much easier sedge to recognise in the field is the Hairy sedge C. hirta. It has hair tips to its leaves and fruits which no other British sedge possesses.

Lastly the most unforgettable sedge to be found has to be a “grove” of Great Tussock sedges C. paniculata. This sedge forms strange-looking upright “pillars” which can sometimes be up to a metre and a half in height.

These pillars often come straight out of water and in numbers have an odd unworldly quality. At one time they were cut, dried and used as foot stools in churches. Fortunately, it still hangs on in parts of the Colne valley and can even still be found in the Ravine bog on Wimbledon Common.

Most rushes are also now developing their fruits which often are more noticeable than their flowers and more useful for identification. A lot of our rushes are either rare, difficult to find or now extinct in London mainly due to the loss of habitats such as fen. As some rushes just have a single small compact elongated flowerhead they are even missed by botanical recorders but it does mean there may be a chance of a discovery. Old Park Wood and Denham Lock wood in the Colne Valley still possess some fen and may be worth exploring.

The Bristle Club rush Isolepsis setacea is one such rush but unlike most others is catholic in its tastes. It can be found in wet meadows, at the sides of lakes, fen, sandy ground as well as on gravel, dunes and even saltmarshes. Consequently it is found all over Britain including London. The similar-looking Needle Spike rush Eleocharis acicularis is more restricted to the sides of ponds or lakes and the Floating Club rush Eleogiton fluitans may well be submerged in slow-moving rivers with just its flowers and fruits showing above the surface.

Rather more impressive is the Sea Club rush or Saltmarsh bulrush Scirpus maritumus. This is an altogether larger and sturdier affair. It is up to a metre tall with a distinctly 3-angled stem indicating it is really a sedge. It can be found along the muddy edges of the Lower Thames and similar environments across the world. Of more interest to Londoners in the past is another sedge Galingale Cyperus longus.

Although now rare it is still planted sometimes as an ornamental. Medieval Londoners made its leaves into hats and its violet-scented roots into pokerounce, a spicy scented sweetmeat which was served at the end of meals. There is another smaller galingale C. fuscus that used to be found at the sides of ponds but as London’s ponds disappeared so did it.