The joy of sedge

Sedges are one of my favourite groups of plants. They are not showy. They are difficult to identify when you are first starting off, as you often have to look carefully at small features on their flowering/fruiting parts, which may vary only subtly from each other. But this encourages you to look closely at things you would otherwise not see, opening up a new world of unique structures and their associated jargon, such as ‘utricle’ and ‘glume’. I find it satisfying to identify groups of plants that take a bit of time and effort to get to grips with.

They also make attractive specimens when you dry and press them. Unlike many plants with colourful petals, dried sedges look similar to fresh specimens, so they turn out to be useful for identifying other plants in the future. And many of them are small enough to fit quite easily onto an A4 sheet of paper.

The photo of spring-sedge in flower above shows the cream-coloured anthers on the male spike at the top of the plant, with the white stigmas on the lower female spikes. The pictures in many identification books show very broad, club-shaped male spikes, but they only occasionally look as broad as in those pictures. This is a common species but tends to only grow in fairly species-rich, infertile grassland habitats. The green male glumes (scales) on the male spikes with a brown border, help distinguish it from ‘rare spring-sedge’ Carex ericetorum, which has chestnut-brown glumes, with a very pale border.

Rare spring-sedge is one of the special plants in the Teesdale assemblage. A unique feature of the Teesdale assemblage is that it includes ‘southern’ plants as well as northern arctic-alpine species. Rare spring-sedge is one of the rare, southern plants that have their most northerly British populations in Teesdale.

The (badly focussed) shot of long-stalked yellow-sedge above was from a pool in Middleton quarry. It’s normal habitat is species-rich calcareous flushes, where you often find other interesting plants, so it is always a good one to find. Each flowering/fruiting stem has several yellowy-green female spikes, which are quite fat and spiky, with one narrow, pale brown male spike on a stalk at the top. Not all sedges have separate male and female spikes like these, or even separate male and female flowers.

The flowers of flat sedge are all bisexual. The genus Carex is the by far the largest sedge genus in Britain, but we have at least 13 other genera from the sedge family. All other British sedge genera apart from Carex have bisexual flowers. Flat sedge is uncommon in Britain and has declined massively in recent decades, so that it is now regarded as a threatened species. The ‘flat’ part of the name refers to the inflorescence being more-or-less flattened in one plane, which isn’t obvious from the picture below, but is obvious when you see it.

We still have some large populations of flat sedge in here and there in Teesdale. One of it’s favourite habitats is alongside upland rivers and streams, in species-rich grassland that is flooded regularly when the river is in spate.

A superficially similar-looking species is false sedge (below), but its inflorescence is not flattened in one plane. It has separate male and female flowers, but they are mixed together in the same spikes.

The ‘false’ part of the name comes from the fact, that previously, it was regarded as being closely related to the genus Carex, but not quite close enough to be included. It differs from other Carex species in having an open utricle (covering around the nut). Its old scientific name was Kobresia simpliciuscula and as it was the only species in that genus, people tended to refer to it just as ‘Kobresia‘. Following recent DNA work, it has now been included in Carex, so we can no longer validly call it Kobresia. That is annoying, as I don’t find it easy to pronounce the species name ‘simpliciuscula‘.

False sedge has a much smaller national distribution than flat sedge. Its main British distribution is in the highlands of Perthshire and Argyll and the only other British populations are in Teesdale. In the right habitats in some parts of Teesdale it is super-abundant. There must be many millions of plants here, making it the most abundant of our special plants.

Not many of the other really special plants of Teesdale are sedges. We do have big populations of hair sedge Carex capillaris, which is mainly a plant of the Scottish Highlands, but occurs in a few other places in northern England and north Wales.

Maybe the most interesting sedge we have is sheathed sedge Carex vaginata. This is another species mainly of the Scottish Highlands in Britain and was discovered new to England in 2002 when the Foot-and-Mouth epidemic meant that many areas of the high fells were left ungrazed for a year. Sheathed sedge was found flowering on Dufton Fell by Rod Corner that year and once local botanists got to know it (particularly its vegetative features), they found several more populations in the higher parts of the North Pennines. Since 2002 however, it has not been common to find it flowering again. It seems to be able to persist vegetatively without reproducing for long periods.