Land Quillwort – very low numbers on Mullion Cliff sites 2012/2013?

Feb 18, 2013 by

Land Quillwort – very low numbers on Mullion Cliff sites 2012/2013?

David Pearman and I had a quick visit to the Lizard on Sunday 17th February 2013 to have a look for Land Quillwort Isoetes histrix at 16 of the 18 mapped colonies (that were found in 1982) on Mullion Cliff SW6617 (map on page 17 in Frost et al., 1982). We found 3 plants only, at one site (210 counted in 1982). We searched short turf, around outcrops and coast paths, including a site where on 13th March 2012 (see photo 1 and 2 below) we saw ‘100s’ (not the 5,513 as counted in 1982). We are both reasonably confident that we could distinguish Isoetes histrix from the other ‘lookalikes’ – Festuca spp., Scilla verna, small Plantago coronopus etc. BUT we saw no convincing plants of Isoetes histrix in 15 sites.

Once you get your eye in you can pick out the small rosettes of thin ‘leaves’ (like Catherine wheels) easily in open patches of ground or turf and in more closed turf it can be difficult, but the fresh Isoetes histrix leaves are a bright green, and when older they develop a ‘bronzy yellow-green’ tinge which, though has a shine, is not as glossy as Scilla verna. Later in the spring – April/May onwards – the plants yellow, making it much easier to find plants in turf.

We don’t know what the reasons are for the apparent demise of Isoetes histrix in most of the 18 sites on Mullion Cliff, as the cliffs have been (and are currently) grazed and most of the outcrops have short turf – it all looks OK, and should get better with continued grazing. I know some of the Lizard sites have had some deep burns in the past, and some sites mentioned in the 1982 report have no recent records since then (or since 1984 or 1995). Were colonies wiped out after a deep burn after 1982?  Perhaps it is the combination of wet summers/dry springs/cold winters for plants not appearing? It is most confusing as some sites, such as south of Holestrow, have large, fine
Isoetes histrix plants at present.

If anyone has seen Isoetes histrix in other sites on the Lizard (or have definitely NOT seen
Isoetes histrix in well-known and recent sites) please let me know.

Ian Bennallick

*Frost, L. C., Hughes, M. G. B., Nichols, C., & Lawman, J. M. (1982). A Total Population Estimate of the Land Quillwort (Isoetes histrix) at the Lizard District and Recommendations for its Conservation. University of Bristol Lizard Project; Report No. 4. Bristol, University of Bristol.

Land Quillwort plant on Mullion Cliff March 2012  copy

PHOTO 1. Land Quillwort (Isoetes histrix) on Mullion Cliff 13th March 2012

 

Mullion Cliff March 2012 Isoetes habitat copy

Photo 2. Mullion Cliff habitat for Land Quillwort (Isoetes histrix) on Mullion Cliff 13th March 2012. Fred Rumsey and colleagues from the Natural History Museum are looking for plants in the very short grazed turf.