How to identify common UK grasses
Martha Boalch, 30/04/2018
When looking at grasses it is important to distinguish them from sedges and rushes. The three plant types are in different botanical families, but because of their similar appearance they are collectively are known as graminoids (plants with a grass-like appearance). They are all wind pollinated so have very light pollen and small or no petals – as they do not have to attract insects for pollination.
The difference between sedges, rushes and grasses
- Sedges form the Cyperaceae family. The solid or pith-filled stems of sedges tend to have defined edges to their often triangular shape, and leaves in three ranks. The flowers are in spikes and the fruit is a single-seeded nut.
- Rushes form the Juncaceae family, they have solid or pith-filled stems that are generally round or rounded. Their flowers grow in clusters at the end of the stem, sometimes with a bract that grows up and looks just like a continuation of the actual stem. The fruit is a many seeded capsule.
- Grasses form the Poaceae family, their stems are generally hollow and cylindrical with swollen nodes. They have alternate leaves in two ranks and small inconspicuous flowers. The fruits are grains.
There are about 12,000 grass species worldwide ranging from wheat to bamboo. Some grasses have important economic roles to play, the four grasses described here are important food sources for the caterpillars of butterflies such as the Essex skipper and the marbled white, they also provide excellent habitat for a range of other invertebrates.
How to identify four common grass species:
Meadow foxtail (Alopecurus pratensis)
Meadow foxtail grows in dense tufts and its signature flower head is the best way to identify this grass.
- The leaves are approximately 5 millimetres wide and hairless.
- The flower head is a long cylinder at the top of a stalk. It has short silky hairs giving a bushy effect.
- Not to be confused with Timothy grass (Phleum pratense) which is a coarser grass that flowers later in the year.
Where and when to find meadow foxtail:
The grass is visible all year round and flowers from April – June. It is typically found across meadows and other grassy areas that are moderately fertile and moist. It can be found along roadsides and bordering hedgerows.
Yorkshire fog (Holcus lanatus)
Yorkshire fog grass is a common species that grows in dense tufts of up to 1 metre tall throughout the UK.
- Leaves are grey green in colour and have hairs to make them look and feel soft. The scientific name ‘lanatus’ means woolly which also corresponds with the leaf texture. Some people refer to it as velvet grass.
- The flower heads grow on the end of the stalk and have a purple to red tinge.
- Not to be confused with creeping soft grass (Holcus mollis) which has a similar appearance but is often found in woodland habitats.
Where and when to find Yorkshire fog grass:
Its visible all year round but flowers from May – June in all grasslands and wasteland; particularly damp or waterlogged areas. It is common.
Cocksfoot (Dactylis glomerata)
Cocksfoot grows in dense tussocks which can be between 20-140 centimetres tall. Its key characteristic is a flattened stem base which separates this grass from others.
- Leaves are grey green in colour, they are approximately 20-50cm long and 1.5cm wide.
- The flowers have a distinctive tufted triangular flower head made up from several clumps of spikelets which hold the flowers. The colour of the flowers can change dependant on the time of year, they are mostly green but have red or purple ends. The flowers turn a pale brown when ready to seed
Where and when to find cocksfoot grass:
It can be found all year round but is best seen from June to September when flowering. It’s very common throughout the UK in meadows and along roadsides.
Timothy (Phleum pratense)
Timothy grass is a popular agricultural grass and is common in a lot of pet feed. Many people are allergic to its pollen. Characterised by the cylindrical flower head, Timothy grass grows in clumps that can be as tall as 1 metre.
- The leaves are smooth and hairless, pale green in colour. Young leaves are rolled and become flat and pointed over time.
- Flowers are located on the end of a stalk and they are densely packed into a cylinder. This cylinder is formed of tiny horned spikelets.
Where and when to find timothy grass:
It is visible all year round and flowers from June until September. It is found in pasture grasslands, meadows and on the side of roads across the UK.
On Nature’s Calendar our recorders observe the first flowering dates for four species. Grass flowers are very small and arranged in clusters. Recorders report first flower when they can see an anther dangling from one of the tiny flowers. A magnifying glass may be required!
Last year we received 835 records of grass first flowering for all four species combined (255 cocksfoot, 219 meadow foxtail, 160 timothy, 201 Yorkshire fog). Meadow foxtail is in the lead so far for 2018, we are looking forward to a good crop this year!