Small cow-wheat

What action is going on for this species?

The following will give you information on what work has been taking place through the Species Action Framework:

• Updates on recent action 
• Action up to start of SAF, April 2007 

Species background

Small cow-wheat (Melampyrum sylvaticum) is an annual herb with a yellow flower, found in upland woodlands.

Why is this on the Species Action List?

This species meets criterion 1a of the Species Action Framework, as a species for conservation action because it has declined substantially in the UK and for which Scotland is now a stronghold.

Recent research has improved our understanding of the species so that targeted actions could be undertaken to instigate recovery.  These actions could also benefit other species such as insects in the same habitat.

Small cow-wheat is a UKBAP Priority Species and is included on the Scottish Biodiversity List.

Habitat, distribution and abundance

Once widespread in Britain and Ireland (over 200 sites) small cow-wheat is now restricted to only 18 sites, most in Scotland north of the Highland Boundary Fault.  At lower altitudes this species occupies high humidity sites - close to water, north-facing and under a closed canopy.  At higher altitudes the climate is cool enough to maintain adequate moisture levels without a dense canopy, although the shorter growing season constrains plant size.

There are many more potentially suitable locations for the species than those it occupies. Extant sites have all been undisturbed for more than a century indicating that the species has a strong requirement for stable conditions.

General ecology

Research has demonstrated that there is low genetic diversity both within and between the populations - not surprising in an annual plant with small, isolated populations.  The seed is exceptionally large for an annual species: annuals usually rely on the production of many tiny seeds to ensure their reappearance each year.  The small cow-wheat seed has an elaiosome, an oil body on its surface, which attracts wood ants that carry the seed to their nests.  Wood ants rely on sun patches in the canopy to maintain the temperature of their nests and in this way the seeds are carried to sites suitable for maximum growth within the woodland.

History of decline, contributory factors and current threats

Some populations appear to have been lost due to habitat changes resulting from fertilizer runoff, intense grazing and the planting of conifers.  The species is undergoing a rapid decline.  This is partly due to change in the management of woodlands but a crucial factor appears to be the loss of wood ants due to woodland management and fragmentation.

A critical factor now seems to be the loss of genetic diversity.  The annual life cycle, with self-fertilization, enhances the likelihood of genetic drift causing loss of diversity in these isolated populations.  The breakdown of the symbiotic relationship with the loss of wood ants reveals the parallel losses in species composition that are evidently occurring in these woodlands.

The 'Species Lead' at Scottish Natural Heritage

Robin.Payne@snh.gov.uk  Tel 01738 458569