Let us choose for the wreath a flower so small
Even you haven't spotted on the dune-slack
Between Claggan and Lackakeely its rosette –
Petalwort, snail snack, angel's nosegay.
from Petalwort, by Michael Longley
Among the many bound pages that still thump through the maw of our wide predigital letter box I am privileged to receive hard copies of the Irish Wildlife Manuals published by the National Parks and Wildlife Service. They share with me the endless research demanded by EU directives for conservation of the Republic's natural world.
From time to time one of them will also remind me of the science that interleaves with the poetry of this particular landscape, both of rare quality.
The latest manual to arrive, number 90, is called Monitoring Methods for Petalophyllum Ralfsii (Wils) Nees & Gottsche (Petalwort) in the Republic of Ireland , a document of 150-plus pages by Christina Campbell, Nick Hodgetts and Neil Lockhart. Its subject is a rare – or rareish – liverwort, one of those miniature beauties of botany called bryophytes, often best admired by humans through a magnifying lens. It also happens to figure, as excerpted above, in a fond accord with Michael Longley, long a summer neighbour, for the companionable disposition of our ashes.
Petalwort, looked at very close, is quite as pretty as a flower. It’s like a brilliantly green and frilly looseleaf lettuce, often just a few millimetres across. But its simple cellular structure, called a thallus, doesn’t actually have roots or leaves, and it produces spores for reproduction rather than flowers and seeds. It anchors itself into the moist sand of humid dune slacks, and its “leaves” can disappear altogether in a hot summer.
How rare it actually is across its European range has undergone a changing measure. But what now seems likely is that Ireland has more petalwort on its moist coastal dunes and machair swards than anywhere else in the world. Indeed, of the 300-odd "rare and threatened" bryophytes of Ireland, grouped in a recent heavyweight tome (the postman had to knock), Petalophyllum ralfsii is one of those accorded "least concern".
The very abundance of the liverwort, however, established only in recent years, makes Ireland the European (if not global) stronghold of the species. And this, through an EU habitats directive, obliges a systematic return to its locations every six years to make sure it’s all still there – and if not, why not. At all 30 Irish sites surveyed for the new report its prospects are happily recorded as “favourable”.
Almost all the sites are on the west coast, from Co Donegal to Barley Cove, in Co Cork. Record populations of more than five million plants have been estimated at a remote stretch of machair plain at Truska, on the Slyne Head peninsula in Co Galway.
The dunes and machair below me at Thallabawn have also made a notable contribution – “hundreds of thousands” of petalwort thalli were flourishing in 1999 and plenty still in 2010, with the close grazing by sheep and rabbits essential for their growth. If I want to find the plants now the best place to look would be in tractor tracks on the mossy surface of the machair.
Golf courses, caravan parks and hotels can all obliterate the delicate, finely balanced habitats of the plant – such development has destroyed the very first location found in Ireland, near Malahide, in 1861. That leaves its only east-coast home on North Bull Island, in Dublin Bay, where two thalli were found on the edge of a track tightly grazed by sheep and a few more in a dune slack farther on – this by Dr Neil Lockhart of the NPWS, the leading prospector of petalwort, in October 2012.
His field notes can speak of hours spent on lonely dune systems, perhaps peering after petalwort between discarded junk and the scars of teenage quad-biking.
And the six-yearly fine-scale monitoring of established sites is even more methodical and exacting. As described in the new NPWS report, specialist bryologists set forth with kits that include a lot of little white sticks (for defining the boundaries of colonies) and bunches of cocktail sticks, one for each individual thallus, planted while kneeling down with a hand lens, perhaps for half an hour or more, at each metre-square sampling plot.
A trowel is also needed to find the level of the groundwater, and a ruler to measure how far down it is. There’s a lot of filling in on the survey card.
The role of petalwort in the biosphere is that of a specialist pioneer plant. Its colonising mats help to stabilise exposed sand against the pull of wind and soak up eroding water. This, of course, apart from making nosegays for angels and passing snacks for snails.