The uncertain distribution of Cat's-tails in Shropshire

Shropshire Botanical Society - Spring 2000 - pages 15-16

Roger Green

 

Introduction

There are approximately 15 species of the genus Phleum found in the temperate regions of the world, of which five are native to the British Isles and, of those, just two - Timothy, P. pratense, and Smaller Cat's-tail, P. bertolonii - are recorded in VC 40 Shropshire.

Both species are widely planted for grazing and hay pastures from selected strains. Timothy is common in field margins, roadsides and waste places, but probably native only in water meadows and damp grassland (Hubbard 1984). This distribution is borne out in the Flora (Sinker et al. 1985) where no distribution map was published and with the additional comment "Frequent throughout lowlands, less so in hill country". For Smaller Cat's-tail however there is some confusion. The distribution map given, at subspecies level, shows the majority of sites in five of the southern 10km squares and the statement "is common in the uplands but its distribution and ecology not reliably separated from type". The purpose of this article is to examine whether the latter really is more common in the uplands, or whether it may be under-recorded more generally.

One approach would be to examine other data sets and see whether there is a similar distribution elsewhere. Accepting that a distribution of a species in the county should not be taken from NVC data when so little of the county was surveyed, it is stated that the data is based primarily on floristic information and therefore assumptions could be made on what you would expect to see in, for instance, neutral or calcareous grassland. So in the mesotrophic grasslands MG5 and MG6 or the calcareous grasslands CG2 and CG3 one would look for equal coverage of the two species, but that is apparently not so on the plains of Shropshire. And you would not expect to find Smaller Cat's-tail to be noticeably more common in the southern hills.

A point could be made that a geographical split of the two species would still give the same result in the data since both have no effect on the NVC classification, however all authors are in agreement that both are cultivated and naturalized widely.

Looking at the "Key for the Identification of Grass in Turf" (Hubbard 1984), presumably a standard work at the time of the NVC contract, the last couplet that splits the species is as follows:-

Leaf-blades 2-5mm wide. Ligules 1-4mm long. Sometimes with leafy stolons. Phleum bertolonii

Leaf-blades longer and wider up to 9mm, perhaps twisting. Ligules up to 6mm. Phleum pratense

In (Clapham et al 1987), the only applicable statement for turf identification of the then subspecies is:-

Subsp. pratense, ligule obtuse.

Subsp. bertolonii, ligule acute.

Spikelets of Timothy and Smaller Cat's-tail

Above: spikelets of Timothy and Smaller Cat's-tail

 

With such a large overlap in the measurements, and the ligules both pointed albeit at different angles, there may be a strong bias in the NVC data towards the smaller plant. So is there:-

1) a similar distribution of the two species within the county which may be hidden by imprecise recording to date, or

2) is there an ecological reason for Smaller Cat's-tail not to compete for instance, in rank roadside verges where it would be allowed to flower with easier recognition, or

3) is the NVC data biased?

 

Conclusion

If we compare the distribution of Smaller Cat's-tail as given in available data with a Soil Association Map (Burnham & Mackney 1964) we can see that it has a probability of being recorded in Soil Association 1 (leached brown soils and calcareous soils) by a factor of four above all other Associations. This accords with the NVC data where Smaller Cat's-tail tends towards calcareous grassland but is also found on a broad spectrum of soils, and it is probably native and would naturalise more readily in the calcareous conditions. As seen from the Flora data 1970-1983, the significant records from the North West of the county were not available to the authors, hence the comment "common in the uplands". However it would appear that Smaller Cat's-tail could be recorded in the pastures, meadows and leys of the Shropshire plain but it will require a careful approach to recording to find it. It is most likely to turn up in fields where it would have been sown, originally, rather than on roadsides and unfarmed land; and it may be necessary to scrutinise a sward closely if it is to be identified in its vegetative form. As general practice, all new records of Smaller Cat's-tail should be supported by a voucher specimen, especially if away from the limestone.

 
Timothy distribution map Smaller Cat's-tail distribution map

Distribution maps of Timothy (left) and Smaller Cat's-tail (right). Open circles represent records before 1985. Timothy was an "A" species and was not recorded during Sinker's Flora Project - it is probably ubiquitous. New records for Smaller Cat's-tail have shown that it is relatively common on the limestone in the Oswestry area and along the Montgomery Canal.

 

References:-

Burnham, C.P. & Mackney, D. 1964. Soils of Shropshire. Field Studies Vol. 2. No 1.

Clapham, A.R. et al. 1987. Flora of the British Isles (3rd ed.) Cambridge University Press.

Hubbard, C.E. 1984. Grasses (3rd ed.). Penguin.

Rodwell, J.S. (ed.) 1992. British Plant Communities, vol. 3 Grassland and montane communities. Cambridge University Press.

Sinker, C.A., Packham, J.R., Trueman, I.C., Oswald, P.H., Perring, F.H. & Prestwood, W.V. 1985. Ecological Flora of the Shropshire Region. Shropshire Trust for Nature Conservation, Shrewsbury.

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