11-July London’s July Grasses

Two very common Cat’s-tails that are likely to be noticed now are Timothy grass Phleum pratense and the Smaller Cat’s-tail Phleum bertolonii. The first is a very attractive grass said to improve any landscape it grows in. It can reach one and a half metres in height and have flowerheads up to 15 cms. in length. It is very at home in fertile pasture where it is often used to make hay. Its green panicles may be slightly pink or white and at this time of year be covered in lavender coloured anthers. The panicle itself is rounded at both ends which can help a field identification. Smaller Cat’s-tail is just like a smaller version of Timothy grass, often less than half its size. The two often grow together.

Two rarer foxtails that might be seen in July are the Marsh foxtail Alopecurus geniculatus and the Slender foxtail or Black grass A. myosuroides. Marsh foxtail is found beside lakes and rivers or in water meadows where it may even be partially submerged. Its “knees” i.e. sharply bent stems, can help to identify it. The Slender foxtail prefers much drier places such as waste areas and roadsides. Its panicles are distinctly tapered at both ends and are often tinged with purple.

The bromes are a larger group of grasses that are often more difficult to identify. They are generally recognised by their medium size and loosely branched panicles with more torpedo-shaped spikelets and long awns. A very abundant species on chalk downland is the Upright brome Bromus erectus whose stems and flowerheads all point upwards from dense tufts. Another very common brome, but in woods, is the Hairy or Wood brome B. ramosus. This has the typically long spikelets but in this case they hang down elegantly. Its hairy leaves can secure an identification.

The brome we see the most of is Barren brome already mentioned earlier in the year but the Soft brome B. mollis is equally common in areas of waste ground. Its spikelets are held erect like the Upright brome but are usually distinctly fatter.

Its leaves are very hairy and soft to touch. Another brome of disturbed ground is the Slender Soft brome B. Lepidus which is just like a smaller more slender version of Soft brome. Meadow brome B. commutatus is also similar to Soft brome but with longer branches that droop more. Its habitat includes meadows as well as waste areas.

Other rarer bromes in London are best looked for in their preferred habitats. The Smooth brome B. racemosus likes water meadows such as those at Chertsey. The Great brome B. diandrus is a much stouter affair with long spikelets and long branches and may possibly still be found on Walton common. The Awnless brome, which has translucent ends to its spikelets, shows a preference for railway embankments.

False bromes Brachypodium spp. although very similar to true bromes tend to hold their spikelets closer to their stems. Two found in London are the Wood False brome Brachypodium sylvaticum and the Chalk False brome B. pinnatum, also called Tor grass. The first is found in woods and has leaves with a strong white central nerve to help identify it and the second is a grass of chalk downland with spikelets that all tend to point in the same direction.

Oats are a little more familiar to many of us with their large often open panicles, glossy spikelets and projecting bent awns. These awns can react to quite small changes in humidity from straight in wet conditions to twisting significantly as they dry.

Yellow Oat grass Trisetum flavescens is the one most likely to be seen. It is a glossy yellow in colour and grows on roadsides as well as in meadows. It is used to make hay as well as straw plait. Its twisted awns are a conspicuous feature which helps to identify it as well as its narrow green leaves, although these may be brown by the end of the month.

False or Tall Oak grass Arrhenatherum elatius is particularly noticeable along our roads and motorway verges. The chief features which help to identify it are its height, which can be up to two metres and its not quite fully open glossy panicles which often seem to fall all one way. Its leaves which can be various shades of green can, like the whole plant, have a slightly metallic sheen. It is bitter to taste which is the reason given for it not being grazed. The Wild Oat Avena fatua is less common but also found on waste ground and occasionally on arable land. It has attractive pale green spikelets striped with a white line and long black twisted awns that were at one time used as fish lures.

The Cultivated Oat Avena sativa is worth looking for in the Epsom area, especially around the stables for obvious reasons. There are many different types so it is hard to identify them further but cultivated oats generally tend to have more leaves, sturdier stems and shorter awns. Other rarer oats can also be found in chalky areas e.g. the Meadow Oat Helictotrichon pratense with its blue-green leaves and bristly tips to its spikelets or the very similar Hairy Oat H. pubescens with its hairy “socks” or bases to its leaf sheaths.

Other than Annual Meadow grass and Smooth Meadow grass which have already been mentioned there are three more meadow grasses (Poa spp.) that might be seen this month. The most common and ubiquitous is Rough Meadow grass Poa trivialis whose leaf sheaths are distinctly rough to touch. The Flattened Meadow grass P. compressa is smaller and rarer but its flattened stems may be noticed especially when it grows on the tops of old walls. Wood Meadow grass P. nemoralis is more typically found on banks in woodland. It is more slender, delicate and attractive than the others which is why gardeners steal it to plant in the shadier parts of their gardens.

Two other types of grass also regarded as decorative may also be seen this month. These are the Hair grasses Deschampsia spp. and Quaking grasses Briza spp. There are only two species of each to be found in our area. Tufted Hair grass Deschampsia cespitosa forms large tussocks on wet heaths with tall, stiff stems carrying dull purple spikelets. The other is Wavy Hair grass D. flexuosa which also has the hair-like branches but they are much more wavy. It prefers drier situations in woods but can also be found on heaths where its pinkish-purple flowerheads, when in numbers, can look like mist. Quaking grasses have to be the easiest of all our grasses to recognise due to their oval or heart-shaped spikelets which hang down and shiver or quake in the slightest breeze.

A walk on chalk downland on London’s southern border is sure to reveal Common Quaking grass Briza media announcing its presence by its trembling flowerhead. There is another larger species, Great Quaking grass Briza maxima which is usually only ever seen in gardens or flower arrangements.

One or two other grasses of note can also be seen this month. Mat grass Nardus stricta is a grass more at home on mountains where it can cover whole hillsides and is responsible for the yellow and brown colours we see in such landscapes. It is small, tough and too wiry to be eaten by sheep and can be recognised by its spikelets which are set in two distinct rows and leaves that almost bend at right angles. It can be found on Hounslow heath. Another rarer grass also found on the drier parts of the same heath is Heath grass Sieglingia decumbens. It is also small (40 cms.) with glossy spikelets and abrupt blunt tips to its keeled leaves. In parks and by roadsides there is yet another common attractive grass to be found.

This is the Crested Dog’s-tail Cynosaurus cristatus, the crest involved refers to its narrow one-sided comb-like panicle. Being a strong, wiry grass it is sufficiently hard-wearing to be used in seed mixtures for sports pitches and lawns yet its leaves are also used to make straw hats. The upper sides of its leaves are greyish-green whereas underneath they are usually a darker green.