Sweet grows the green grass | UK Wildlife

While our visitors are being enchanted by large numbers of six-spot burnet moths on chalk downland and adjoining habitats in the Museum’s wildlife garden, less conspicuous species such as the Essex skipper butterfly (Thymelicus lineola) and garden grass veneer moth (Chrysoteuchia culmella) have been spotted flying low amongst meadow grasses and herbs. All three species rely on grasses at one or other stage of their life cycle. 

Photo showing the brown coloured moth at rest on a leaf. It's wings fold over its abdomen giving it a long, narrow shape.

Garden grass veneer moth (Chrysoteuchia culmella)

Frances Dismore tells us more about the importance of grasses: Last summer, on donning the Museum wildlife garden volunteers’ T-shirt with the words “talk to me” emblazoned on the back, I hadn’t anticipated the number of discussions about grasses I’d have with young visitors to the garden. I attribute this to the sheep. Children would stop to ask their names and our conversations inevitably turned to the evident relish the sheep took in grazing the chalk hill and meadows.

I would proffer the speculation that it was an especially charmed existence to have a job guzzling grass seven hours a day and suggested that surely the children would agree since they themselves probably tucked into a heaped plate of grasses every day of the week.

I loved to see looks of sheer incredulity turn to understanding as they made the connection between grass and the seed grains used to make breakfast cereals, bread, cakes and biscuits. Never mind the ecological services they provide; the sheep’s work here was done.

I consequently greatly appreciated the opportunity to attend the introduction to grasses, sedges and rushes course lead by Dominic Price of the Species Recovery Trust, held in the Museum’s wildlife garden.

Dominic encouraged us to use touch and scent as well as observation to find ways past our own plant blindness when trying to differentiate grasses of the meadow sward; which, at first glance, all looked frankly green and dare I say… grassy. His entertaining descriptions made the identification of Poaceae straightforward and accessible.

Photo showing a man holding grass to the right of the image, with three people stood around him listening to what he is saying about the grasses and taking notes.

Dominic Price of the Species Recovery Trust engaging us with grasses

The garden supports nearly 60 taxa of grasses, sedges and rushes. These ecologically important plants are carefully curated in community biomes which provide habitat for the avian, mammal, amphibian and invertebrate biodiversity found in the garden. They support several Tetramesa (Chalcid wasp), Opomyzidae/Diptera (fly) and Lepidoptera (moth) larvae which are obligate grass leaf or stem miners or phytophages and Heteroptera (‘true’ bugs).

Not only are grasses a part of the diet of the larvae of the bagworm moth, they also construct cases from grass fragments which they carry around with them as they feed. When it is time, they adhere the case to a tree trunk or, sometimes, foliage and pupate inside.

The larval food plant of six-spot burnet moth (Zygaena filipendulae) is bird’s-foot trefoil (Lotus corniculatus) but I have observed that when the chalk grassland population in the garden are ready to pupate they climb the tall stems of grass such as false oat-grass (Arrhenatherum elatius) to spin their pupal cases.

Photo showing the two moths on a yellow flower. One moth (right) is at rest, the other (left) has been captured by the photo mid-wing beat as it feeds.

Six-spot burnet moths on a flower in the chalk downland of the garden

I am especially proud that the garden is an ark for nationally scarce plants such as the endangered starved wood sedge (Carex depauperata), a UK Biodiversity Action Plan priority species of which 4 populations are extant in two localities in England; this impressed the ecologists on the course greatly.

My motivation for volunteering in the wildlife garden is to learn to identify native plants to species as I’m interested in biodiversity recording. Learning to identify and understand the ecological characteristics and behavior of grasses such as wood melick (Melica uniflora) or wood millet (Milium effusum) and then spot them on my botanical forays, for instance in Lesnes Abbey Woods a relict wood in southeast London, has proved a personal triumph. In England, wood millet is an ancient woodland indicator, though changes of land use and atmospheric deposition of nitrogen is impacting its range.

The living classroom of the garden provided a unique opportunity to juxtapose species of the same genus and observe in situ the habitat in which they’re found and discuss the implications of this on speciation and plant morphology.

We compared the strap-like leaf-blades of tufted hair-grass (Deschampsia cespitosa) which prefers poorly drained soils with wavy hair-grass (Deschampsia flexuosa) which has needle-like leaf-blades with waxy cuticles which are adapted to the drought-stress of dry grasslands like moors and acid heaths.

By comparing wood sedge (Carex sylvatica) with the very different looking grey sedge (Carex divulsa subsp. divulsa) we learnt to look for the diagnostic triangular culm or stems and separate female and male flower spikes characteristic of a sedge.

It was also informative to be able to compare wood-rushes with true rushes, annual meadow-grass (Poa annua) with rough meadow-grass (Poa trivialis), or false brome (Brachypodium sylvaticum) with soft brome (Bromus hordeaceus), or meadow foxtail (Alopecurus pratensis) with sweet vernal grass (Anthoxanthum odoratum), to mention but a few of the plants we looked at.

This year I’ve been allocated the reed beds to maintain and have spent many an hour weeding with my ears down amongst whispering swathes of common reed (Phragmites australis), reed canary grass (Phalaris arundinacea) and lesser pond sedge (Carex acutiformis).

Photo showing the reed bed in the garden, with a brick path in front, a partial row of trees behind and the south west corner of the Museum building in the background.

The reed bed in the wildlife garden

Riparian plants like these are being employed in the bioremediation of Thames River Basin District waterways. Their respiration vital, vigorous on the back of my neck I’d ponder and marvel at the global success of grasses –  grassland biomes cover approximately 31–43% of the earth’s surface (Gibson, 2009).

Thank you Frances, and also thanks to Tristan Bantock of britishbugs.org.uk for permission to use his photo of Megaloceraea recticornis.

Visit the Wildlife Garden and search for these grasses, sedges and rushes – Open daily 10.00 to 17.40

* Gibson, D. J. (2009). Grasses and Grassland Ecology. Oxford: Oxford University Press.