Yorkshire Fog – "a little bit of Yorkshire"
I have been writing a regular Nature Notes column for almost six years, but until now I have avoided talking about one of our most important and difficult plant families – the Grasses (Poaceae).
Grasses are one of our largest plant families; 12,000 species worldwide, with 220 species in the UK. Grasslands cover 40% of the Earth’s land surface, and account for 45% of the calories we consume as humans. As major civilizations slowly developed (roughly 10,000 years ago), wild grasses with exceptionally large grains were brought into cultivation and have slowly evolved into the food we eat today:
In China there was Rice.
In South America there was Maize.
In Europe within the Fertile Crescent (modern day - Middle East), there was Wheat and Barley.
And in Africa there was Sorghum and Millet.
Grasses evolved earlier than was originally thought, probably around 82 million years ago. Unlike most other plants that grow from the tip, grasses have their dividing cells at the base of the plant. This means that if shoots are grazed by herbivores or livestock, new shoots will continue to grow from the base. Many botanists shy away from grasses - they can be difficult to identify. In the first place, they don’t have petals you can count, colours you can categorise or leaves that are easily distinguished. Secondly, they come with a whole new glossary of terms, and finally they all look so ‘samey’.
I think everyone should recognise at least one Grass. I have chosen to highlight one very common species found throughout the UK and northern Europe. It also has a local connection, its name ‘Yorkshire Fog’ (Holcus lanatus). It is said that Yorkshire Fog was given the name because, from a distance, it resembles the smoke that once billowed from the chimneys of northern factories. This is especially so before the flower head or panicle (inflorescence) fully opens. The hairy stem or culm acts as the ‘chimney’ . If you then look at the stem base, there are longitudinal pink lines. Botanists often referring to these as ‘stripey pink pyjamas’
A very similar looking grass Creeping Soft Grass (Holcus mollis) can be identified from Yorkshire Fog, by its very hairy nodes, and absent stem hairs. Another botanical mnemonic referring to the specific Latin name ‘mollis’ is ‘Molly has hairy knees’
Next time you are on your travels, and you spot Yorkshire Fog, think to yourself – ‘It is always nice to see a little bit of Yorkshire when you are away from home’.
It can sometimes be difficult telling the differences between Grasses, and similar looking Sedges and Rushes. Which is where the old botanical saying can help: ‘Sedges have edges, Rushes are round, and Grasses have nodes right up from the ground, so what have you found? They all have different flower structures, requiring a x10 hand lens to see any detail and beyond the scope of this article. But there are some easier clues, as identified by the saying above.
The stems of Sedges are triangular in cross-section (hence having edges) and are solid, with the leaf blades coming off at 120 degrees (a bit like a Mercedes car symbol) if you look from above.
Rushes are generally round, often containing a continuous or interrupted pith. They were once used to make cheap rush lights to illuminate houses and is where the saying ‘burning the candle at both ends’ originates.
Grass stems are hollow, and are the only ones to have nodes, from where the leaf sheath and blade arise. Pull back a leaf blade from the stem, and where it joins the stem to become the sheath there is often a tongue-shaped ligule. The leaves, unlike Sedges, are also in pairs, ie. at 180 degrees to one another.
Even if you are not tempted - to start identifying this complex group of plants, do take time in the coming summer months to take a path through an uncut meadow. As the wind gently moves the sward, sit down, take time to listen and watch the swaying grass - it is beautiful.
Postnote: The anecdote about Yorkshire Fog being ‘a little bit of Yorkshire’ initially came from David and Nyree Fearnley.