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Cowslip - Primula Veris

This is probably the species for which we have the most complete information, so it will be analysed in more detail than the rest. It is easily visible in April-early May, but stops flowering in late May, by which time it is hidden amongst tall-growing grasses. The first map shows it to be widespread, with "cowslip central" located in the centre of the Hudnalls, but an almost complete absence from the limestone plateau, save for a few on road verges. The few old records date to the 1990s. A second map gives an idea of the size of cowslip populations: in particular it shows that some are small, just single plants or two or three, well away from the next known cowslips.

Survey Results Map

In 1920, cowslips were abundant in pastures, hedge-banks and open woods, i.e., managed woods with grassy rides. Flora Klickmann records them as lavishly in flower (01/05/1924); beautiful in Cowslip Rise (24/04/1929); a great year for cowslips (23/04/1949); and very prolific this year (10/05/1950). The Gloucestershire Flora records them as plentiful on the calcareous soils in pastures and meadows.

Cowslips are grassland species that can stand only limited shade. They prefer base-rich soils and seem to dislike anything heathy, but seem fairly agnostic about soil moisture, avoiding only the wettest ground. Young plants understandably look small and flower weakly, if at all, in their first spring, but they can live for decades. Their seed generally falls at their feet so they are slow to colonise newly suitable ground at a distance from existing plants.

An assessment of their overall population in the two parishes depends not just on dots on a map, but also observations of the size of individual populations represented by each dot. Most populations are small, and some are no more than one, two or three plants. Each is likely to be isolated from the next, except where adjacent fields both have cowslips, in which case pollinators can readily transfer pollen from one to the other (If we hear of any instance of cowslips ‘appearing from nowhere’, i.e., colonising at a distance, that would be encouraging.)

My assessment is that cowslips have declined substantially in the last 100 years and may still be declining slowly. The evidence for the latter is:

  • A few places have evidently lost cowslips since the 1990s.
  • A few populations consist of just 1-3 old plants: they are very small and not reproducing.
  • Many more populations, including those on road verges, are small (say, less that 30 plants). If, as I suspect, they are isolated, they will be less likely to be pollinated; will set less seed; and will be vulnerable to in-breeding depression. They are populations at risk.

However, cowslips are not likely to die out in the parishes because:

  • A few large populations survive, and will continue to flourish while the present management is sustained.
  • Many gardeners carefully mow round cowslips on their lawns. In fact, I suspect some lawn populations were planted.

Why have cowslips declined and why are they still declining? Building on local evidence with experience elsewhere, I think the main reasons are these:

  • Ploughing and fertilising fields, converting grassland to arable crops or improved leys.
  • Fertilising pastures that were not ploughed. Cowslips cannot compete with taller herbage.
  • Decline in numbers of cattle and replacement with prolonged sheep pasturage.
  • Decline of coppicing and other woodland management, which eliminates woodland grassland.
  • Withdrawal of grazing from verges, leading to rank herbage, and overgrowth of scrub and hedges.
  • Abandonment of fields and failure to manage grass under new orchards.
  • General spread of nitrogen through the environment, which makes road verge vegetation even more rank.
  • Suburbanisation of gardens, including herbicides on lawns.

Cowslips may also be facing a more insidious threat from closely related species. Several populations include false oxlip, the hybrids between cowslips and primroses, and a few even have red cowslips, the spectacular hybrids between cowslips and garden cultivars. Fears have been expressed elsewhere that primroses and garden polyanthus are hybidising cowslips out of existence. However, my guess is that this is a curiosity, not a threat.

Survival of cowslips depends on:

  • Large gardens, where some survive on less-intensively managed parts of lawns.
  • Actual deliberate preservation by not mowing when in flower.
  • Survival of a few paddocks and meadows without fertilising and with continued grazing after May.
  • Leaving some road verges undisturbed by utilities and ensuring that they are mown late in the season. It is also necessary to trim the hedges, lest they shade the verges.

Verdict:

  • Survey information reasonably good.
  • Continued decline is likely, especially on verges, mitigated by scatter of garden owners who like cowslips enough to take care of them.
  • The best populations depend on the owners of a very few fields.

George Peterken