2024 County Report for North Wiltshire, South Wiltshire

Richard Aisbitt and Kat Newbert

Following our work for the BSBI Atlas 2020, the Wiltshire Botanical society has been completing a survey of the county at one-kilometre square scale. During 2024, we made around 40,000 new records. This brings us down to 68 monads with few or no recent records, out of of around 4,000 in Wiltshire. Some of the under-recorded monads are difficult or impossible to access on the Salisbury Plain Training Area, but we hope to fill many of the gaps during 2025.

With all this data, we plan to produce a new county flora; the last one was published in 1993. A small group has been exploring options for publication, both in book form and on the web. We are busy looking at the occurrence data for all the Wiltshire taxa and planning the writing of species accounts and longer articles.

The previous Wiltshire Flora was based on a full county survey, so we now have two data sets to compare. We can use the raw counts and distribution maps for each species, but statistical analysis like that used for Atlas 2020 (and the England Red List) would tell us more. This analysis was based on Mark Hill’s Frescalo software, which compensates for differences in recording effort, and provides confidence limits for the changes seen. Colin Harrower and Oli Pescott worked on the data for Atlas 2020 and have provided me with advice and computer code to carry out the analysis. It is a work-in-progress, but hopefully will give us more confidence in assessing any changes in plant distributions.

Many of our new records are garden and farm plants escaping and establishing themselves in the wild, but a number of other interesting plants have made a first appearance. The most spectacular and unexpected of these was Bladderwort Utricularia australis, which appeared in a recently cleared and re-profiled woodland pond. It was abundant across the pond and flowered profusely, which made distinction from the vegetatively similar U. vulgaris possible. Its origin is unknown, but it could have come from fragments carried on a bird’s feet.

The orchid hybrid Ophrys × flahaultii  (O. apifera × sphegodes) was another surprising and unusual find, appearing on a grass verge. One of the parents, O. apifera, is widespread and increasing in Wiltshire, but O. sphegodes has not been seen here since 1989.

We gained a new Bidens, Fern-leaved Beggarticks B. ferulifolia. Another Bidens, plain Beggarticks B. frondosa was first spotted in 2022, and is continuing its progress eastwards along the Kennet and Avon Canal.

Although noticed in 2023, we had our first records for Small Goosegrass Galium murale in both VC7 and VC8. The VC7 plants were in a concrete crack outside my garage! There were also Ivy Broomrape Orobanche hederae and Polypogon fugax, both new to VC7.

That’s the good news. Hampshire-based Tristan Norton and Martin Rand found and mapped Water-primrose Ludwigia grandiflora growing abundantly around Sturtmoor Pond and its outflow (boundary peculiarities put the pond in VC8 South Wiltshire, but in the administrative county of Hampshire). This thuggish alien throw-out will be a challenge to eliminate.

We ran a BSBI dandelion weekend in April based in Devizes at the Wildlife Trust offices (thanks to Jon at the record centre for hosting this), led by the national expert John Richards. Wiltshire was previously poorly-recorded for Taraxacum microspecies, so this was a great opportunity for the 20 or so taraxophiles to put things right. We visited downland and neutral meadow sites in VC7 North Wiltshire, both specialities of the area, topping this up with urban Devizes and some woodland.