Bryophytes in North Wiltshire (VC7)

Activities and highlights in 2010

By Sharon Pilkington, BBS Regional Recorder

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New VC records

Five of 2010’s new discoveries were liverworts. Several should really have been confirmed before as they are pretty common and widespread. Still, it’s never too late to catch up! The large thalloid liverwort Marchantia polymorpha has three subspecies. At Spye Park subspecies ruderalis was found growing in a disturbed area, a typical habitat for it. A few months later, subspecies polymorpha, which is usually found in relatively undisturbed places, was found on the wall of a canal lock at Caen Hill in Devizes. Spye Park was also the location for another new liverwort. Kind permission to survey the estate was given to a small group of us and we were able to make close examination of some of the exciting flush vegetation present there. In places, Greater Tussock-sedge Carex paniculata is abundant and some of the older tussocks leave peaty stools sticking up from the ground. On some of these the leafy liverwort Calypogeia muelleriana was quite common, the first time this species has been recorded in Wiltshire. Another locally rare moss, Plagiothecium latebricola was also found on the sedge tussocks, its first sighting in the VC in 60 years.

An old chalk quarry at Morgan’s Hill provided another first record, for the small leafy liverwort Leiocolea badensis. Its lookalike cousin L. turbinata is a common species of damp chalky ground across Wiltshire and it may be possible that L. badensis has been overlooked, especially in colder north-facing places.

Summer is normally a poor time to find bryophytes in southern England. Warm, dry air means they are normally shrivelled up and they are often obscured by the higher plants. But a visit to an old water-meadow (Cooper’s Meadow) by the River Kennet in Marlborough in August still proved to be fruitful. A heavy downpour the previous day had refreshed the vegetation and obvious epiphytic growth on some of the willows there proved to be a diversion from the higher plants we were supposed to be recording. Among a very good collection of epiphytes which included some less common mosses including Leucodon sciuroides, was Syntrichia virescens, a new record for the area.

Finally, roving bryologist Mark Hill recorded Brachythecium mildeanum new to North Wiltshire during a quick visit to South Marston in April. This is another species that really should have been seen earlier. It is a rather non-descript and scruffy-looking moss that has a preference for trampled ground and disturbed places and it is almost certainly waiting to be found in many more places.

First recent records

John Presland has been undertaking extensive survey work of dry-stone walls in his parish of Winsley, near Bradford-on-Avon. Among some bryophytes he sent me to verify was Bryum radiculosum, a rather nondescript tuft-forming moss which likes to grow on mortar and calcareous rock. This was the first record in VC7 for 60 years. It is not at all rare but seemed that way because nobody had been recording it! I have found it in five other locations in VC7 since then – church walls seem to be a favourite habitat in our area.

In February a Wessex Bryology Group field meeting at West Yatton Down, near Chippenham found Scleropodium cespitans, a moss last seen in VC7 in 1930. I have since found it to be locally abundant in the Cotswold Water Park area, where it likes seasonally wet streams and field drains.

Other news

In December Richard Lansdown and I went searching for one of our rarer mosses. Leptodontium gemmascens (also known as Thatch Moss) is a diminutive moss that grows on sheltered and weathered thatch in southern England. Richard had undertaken a survey of National Trust properties and was fired up to check out some other records. The sole North Wiltshire record was from a small group of thatched houses near Aldbourne. A number of kind householders agreed to let us look at their roofs but we didn’t find it, unfortunately. We moved on to the Lockeridge and West Overton area where there are many thatched houses (and a thatched wall) but were disappointed to see that virtually none of them was unmeshed – it seems that the wire may influence the chemistry of the thatch and L. gemmascens doesn’t like it. Apparently it is standard thatching practice these days – in our area at least – to cover new thatch with mesh to deter birds. We did find one well-decayed and unwired thatch – ironically on a barn at the National Trust offices at East Kennet Farm – but the moss wasn’t there either.

Mark Hill, who manages data for the British Bryological Society, reminded me last year that many parts of North Wiltshire remain unrecorded, even for very common species. With a new national bryophyte atlas due out in the next few years, it is important to get good coverage of recording across the country. I shall therefore be aiming to get to those parts of VC7 that no bryologist has reached before in the year ahead!