Northern Ireland's Priority Species

Melampyrum sylvaticum – small cow-wheat


Distribution map

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Melampyrum sylvaticum L.
Family: Scrophulariaceae

Melampyrum sylvaticum is an attractive, yellow-flowered annual which has become reduced to a handful of sites in Britain and Ireland where it occupies the most westerly extent of its European distribution. Due to identification difficulties, however, the real distribution of small cow-wheat remains unclear.

In brief

  • It is now extremely local in Britain and Ireland and is found only in humid parts of open woodlands in north, central and western Scotland, in Teesdale in the northern Pennines, plus two sites in Wales and three or four in Northern Ireland
  • Small cow-wheat is rare and is found at only a few sites in Northern Ireland and none in the Republic of Ireland
  • It grows in shallow impoverished acid soil that is slightly flushed by mineral-carrying, oxygenated ground water, movement of which carries away the very soluble nitrogen from the plant's shallow roots
  • Cow-wheats can invade the roots of neighbouring ‘host’ plants to steal some of their nutrition. They can live independently if a host plant is unavailable.

Species description
Small cow-wheat is a low, scrambling, fast growing woodland annual of the snapdragon family. The plant grows 5-18cms high and has opposite, narrow leaves. Small, opposite, deep yellow tubular flowers are produced from late June to early August.

Life cycle
Most seed germinates in the spring and the plants flower from June to August completing their life cycle in the autumn, making these summer annuals. The vast majority of flowers are self-pollinated. After fertilization the petals often turn a distinctive bright brick-red or orange colour as they fade — perhaps a visual signal to insects not to bother visiting them. The fruit capsule contains two large seeds, each with a small, sweet-tasting attachment attractive to ants which carry them to their nest and consume the food reward. The still viable seeds are then removed from the nest where they remain until they germinate. Seed transport from the parent plant helps avoid destructive predation by birds and small mammals.

Similar species
Unfortunately, there is a similar and much more frequent relative of this species called common cow-wheat, Melampyrum pratense. The latter has rather larger flowers which are generally paler in colour, or two-coloured — although one variant of it (called var. hians), does produce deep yellow flowers like those of M. sylvaticum. The similarity between these two species continues to create confusion and we cannot be certain that small cow-wheat is not sometimes overlooked, being mistaken for the common cow-wheat. Thus the real distribution of the rarer, smaller species is only poorly known.

How to see this species
The habitats of the two cow-wheat plants are so similar that they can occur together in damp, rather open, light, broadleaved woods, often under birch, mainly in upland tree-lined ravines and glens. M. sylvaticum also rarely occurs in humid lowland lightly shaded woods. Small cow-wheat typically grows in damp but drained, slightly flushed, grassy hollows near water, either in the form of gently sloping wooded lakeshores, river banks or streamsides, and especially by waterfalls. It appears more rarely on less shaded or completely unshaded rock ledges at higher altitudes. Very occasionally small cow-wheat grows under the moderate shade of deciduous bilberry-dominated heath, but only when the soil is sufficiently drained to allow a species-rich sward to develop. These very specific habitat requirements of Melampyrum sylvaticum restrict its ecological range and help explain the current limited British and Irish distribution.

Current status
Previously small cow-wheat was regarded as a Nationally Scarce species, but it has become increasingly rare, disappearing from many previous sites. Numbers may still be in decline. There are 41 records of the species in Northern Ireland in the CEDaR flora database, but only four current populations are known, all in County Londonderry. Decline, if it is genuine, has been extremely rapid, particularly in the glens of East Antrim. The species is protected under Schedule 8 of the Wildlife (Northern Ireland) Order 1985.

Why is this species a priority in Northern Ireland?

  • It is listed as a UK Priority Species
  • It is rare and in decline,found at only a few sites in Northern Ireland and none in the Republic of Ireland, i.e. the Irish population is restricted to Northern Ireland
  • It is an Irish Red Data Book species classed as vulnerable.

Threats/Causes of decline
Research in Scotland indicates that British populations are isolated and suffering the weakening effects of inbreeding. Current threats include agricultural intensification, fertiliser runoff at woodland edges, leading to the growth of rank competing vegetation. Over grazing or the abandonment of grazing are both detrimental, as is plantation of coniferous trees in place of native broad-leaved species. Air pollution involving acid rain and nitrogen enrichment affects other Melampyrum species. In addition small populations are vulnerable to local extinction through chance events such as fire, flood and fungal attack.

Scottish Wildlife Trust is the lead partner for this UK Biodiversity Action Plan Priority Species and it is gathering all known data and searching likely sites to see if we can identify and solve the problem limiting the species. Research projects in Scotland have been underway since 2002 — an MSc genetics study at the Royal Botanic Garden, Edinburgh by Catherine Sharp; continuing surveying and monitoring of sites by Paul Gallagher of the Scottish Wildlife Trust; and Sarah Dalrymple is working towards a PhD on the ecology and conservation of the species at the University of Aberdeen.

Conservation of this species

Current action
There is a UK Species Action Plan which was published in 1999 and a Northern Ireland Species Action Plan which was published in 2005.

  • At least one of the County Antrim sites lies within an existing designated Area of Special Scientific Interest (ASSI) — Glen Burn ASSI
  • The Department of Agriculture and Rural Development (DARD) in Northern Ireland and the National Trust are active in taking action to monitor, conserve and enhance the Melampyrum sylvaticum populations in Northen Ireland
  • Implementation of the Northern Ireland Habitat Action Plans for Mixed Ashwoods and Oakwoods.

Proposed objectives/actions

  • Maintain the current popluation of M. sylvaticum at four sites
  • Maintain the current range of M. sylvaticum at three 10x10km squares
  • By 2015, increase the number of M. sylvaticum populations to five sites
  • By 2015, increase the range of M. sylvaticum to four 10x10 km squares.

What you can do

  • Report any sightings to the local Recorder of the Botanical Society of the British Isles. (Tel: 028 9039 5251 to discover who to contact in your particular location). An authorised field worker will then check the plant identification and add information in your name to the computer database managed by CEDaR
  • Volunteer for any future monitoring schemes or assist with habitat management
  • Avoid excessive trampling or local disturbance around existing sites.

Further information

Flora of Northern Ireland

The Wildlife (Northern Ireland) Order 1985

Northern Ireland Species Action Plan Small Cow-wheat

UK Biodiversity Action Plan

Northern Ireland Habitat Action Plan Mixed Ashwoods

Northern Ireland Habitat Action Plan Oakwood

Glen Burn ASSI

ARKive - Information on Small Cow-wheat

More information on Small Cow-wheat

Many internet sites have incorrectly named photographs of this group of plants. The following site presents 3 correctly identified images of small cow-wheat.

Photos of Small Cow-wheat

Rich, T.C.G., Fitzgerald, R. & Sydes, C. (1998). Distribution and ecology of Small Cow wheat (Melampyrum sylvaticum L.; Scrophulariaceae) in the British Isles. Botanical Journal of Scotland 50 (1): 29-46.

Rich, T.C.G. and Sydes, C. (2000). Recording and the declines of the Nationally Scarce plants Ajuga pyramidalis L. and Melampyrum sylvaticum L. Watsonia 23 (2): 293-297.

Sharp, C. (2003). Genetic variation in small isolated populations of a rare vascular plant — Melampyrum sylvaticum (small cow-wheat), The Biodiversity and Taxonomy of Plants MSc 2002-2003, Royal Botanic Garden Edinburgh.

Text written by:
Dr Ralph Forbes