Monday, 21 May 2018

Spring Atlas recording

May is always a very exciting time of year, and in the few weeks since I last posted there have been two Atlas recording meetings which I have organised, several ad hoc outings of my own, and I have had records from other botanists out recording themselves. I therefore thought I'd share some of the interesting findings from this early part of the season. If you've sent me records or participated in recording events and would like to see how your contribution has added to Atlas progress in the county, then I have updated the interactive Atlas map. I find this a useful tool for targeting my own recording and tracking progress and will update it every week or so.

The target areas for the last couple of my meetings have been rather underwhelming, Tusmore Park (SP53) this last Sunday being very sterile, and Fringford (SP62) two weeks ago also uninteresting. However, without much to keep one in a square there is the opportunity to range more widely and collect a greater number of records from a larger area. Beyond Tusmore on Sunday, we found many nice grassland plants along the A43, with Anthyllis vulneraria (kidney vetch), Briza media (quaking grass), Hippocrepis comosa (horseshoe vetch) and Lithospermum officinale (common gromwell) all new to the Oxon part of SP53. Also new to the Oxon part of the hectad was Carex distans (distant sedge), an uncommon plant of floodplain meadows and fens, found here by a carp pond by the brook that forms the boundary with Northants. It is also a plant of saltmarshes, and within the pond was a very surprising saltmarsh species, Bolboschoenus maritimus (sea club-rush), a county first. It may have been planted, but it is a very unusual choice of planting! It has been known from brackish marshes inland in other parts of England, such as at Marcham in VC 22, but never in VC 23. Salt-loving plants in Oxon are confined to the edges of salted roads, and indeed along the A43 we found the under-recorded halophytes Cochlearia danica (Danish scurvy-grass), Pucinellia distans (reflexed saltmarsh grass) and Spergularia marina (lesser sea spurrey).

I had a very productive recording session at the edge of Bicester early last week, with numerous interesting finds. Without a doubt the most surprising was the nationally scarce fern Gymnocarpium robertianum (limestone fern), growing in the mortar of the retaining wall of the Chiltern railway line. A species of limestone rocks, such as the deep grikes in limestone pavement in the Yorkshire Dales, it was first recorded in Oxon by Bobart in 1699 in a quarry on the Cornbury estate, where it was known for another two centuries, but has not been seen in the county for around forty years. It is grown occasionally in gardens and so its status is somewhat in doubt, but it is a beautiful fern and I welcome its return to our flora!

Recording in an urban setting turns up many indisputable alien plants, of course, and one such which was common on the streets of Bicester was Capsella rubella (pink shepherd's purse). This species may be on the increase locally; I have seen it in a few other places around Oxford but there are few records at present. It is quite distinctive, plants having a strong bronzey-pink sheen to them, colouring the sepals and fruits in particular. The petals are mostly white I have found, but are distinctly shorter than in C. bursa-pastoris, only slightly longer than the sepals, and the fruits are smaller with slightly concave edges. Please look out for this plant and send me your records!

An event run by the Floodplain Meadows Parternship at the Meadow Farm BBOWT reserve in Blackthorn (SP62) on Monday afforded an opportunity to record a really rich site in detail as well as the under-recorded surrounding area. In addition to the many plants for which this beautiful site is well-known, such as the nationally scarce Carex vulpina (true fox-sedge) and Oenanthe silaifolia (narrow-leaved water-dropwort), this turned up a new site for the county scarce Myosurus minimus (mousetail), a specialist of muddy tracks that dry up in summer, and the distinctive Carex vesicaria (bladder sedge), both new to the Oxon part of SP62. There was also a rose that, even at this early point in the year, looked rather like Rosa sherardii (northern downy rose), a northern species which I had never seen in the county and I thought could be extinct. In addition to all this excitement, there was Oenanthe aquatica (fine-leaved water-dropwort) in Blackthorn, a new tetrad for this locally uncommon wetland plant of ditches and swamps.

That isn't all the recording I've been doing over the last week. On Tuesday, BSBI scientific officer Pete Stroh and I went out recording around Middleton Stoney (SP52). Pete had arranged access to the cricket ground in Middleton Park, where we found some lovely limestone grassland dominated by Bromopsis erecta (upright brome), with Avenula pratensis (meadow oat-grass), Carex caryophyllea (spring sedge), Cirsium acaule (dwarf thistle) and Conopodium majus (pignut), all new to the tetrad. There was also a cracking verge just outside the village with limestone grassland and Astragallus glychyphyllos (wild liquorice), and in a disturbed amenity verge in the village Amsinckia micrantha (common fiddleneck), an alien which it is always nice to see and that has very few Oxon records.

We covered a lot of ground around Middleton Stoney, recording in three tetrads. Aves Ditch to the west proved a shelter for a few plants that would stand little chance in the surrounding intensively farmed landscape, but one surprising plant seemed to be thriving on precisely this intensive use. This was the critically endangered Scandix pecten-veneris (shepherd's needle), growing in a huge population, the biggest I've seen by a long way, in winter cereal. There are a couple of records made in the sixties and seventies from fields close by, so it'd be nice to think that this area is a long-existing stronghold for this very threatened arable weed.

The above is just a taste of the many delightful and unusual plants that are out there to be found while recording for Atlas. New plants are always arriving or unlooked for in out-of-the-way parts of the county, and among the joys of recording is knowing you were the first person to find them. I hope that you will find something of interest while out recording on your own or as part of the many local recording meetings this season. I leave you with Pete Stroh's photograph of a small part of the huge Scandix population we found. Gorgeous!

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