|The hybrid violet Viola x scabra showing a mix of hairy and sweet violet traits, notably the hairy petioles and presence of stolons, respectively.|
One of my main recording objectives for this year is to get the hectad SP42 up to scratch: as one can see on the Atlas 2020 page it is a very under-recorded part of the county. I made a start on that objective this weekend by recording around Tackley in the south-east corner of SP42. Nobody seems to have recorded there since the 1960s, not for the BSBI anyway. The two tetrads that cover most of Tackley (SP42Q and SP42V) have a good mix of habitats, with the village, to the east the River Cherwell, its floodplain and the Oxford canal, a Local Wildlife Site (LWS) in SP42Q and two in SP42V, and large and small woodlands scattered through mixed farmland in the area. Given this diversity of habitats, semi-natural and artificial, I felt the area was a good one to choose as part of my recording of SP42. I mostly focused this weekend on SP42V but the churchyard of St Nicholas' in SP42Q looked enticing and so I recorded there also. Of the local wildlife sites, Tackley Heath (SP42Q) and Crecy Hill are open access, which is useful, and a public right of way passes through part of Northbrook Marsh.
|The distribution of wood sorrel in VC 23. Green squares are tetrads with post-2000 records.|
Wood sorrel, in Oxfordshire a plant of ancient woodland mostly in more 'upland' areas. It is common where acid clay-with-flints overlies the chalk in the Chilterns area, where it is very under -recorded (map right). Wikimedia Commons
A couple more Near Threatened plants I found on the verges in the village of Tackley - field scabious (Knautia arvensis) and hoary plantain (Plantago media). Again it is quite surprising that these are Near Threatened, and again shows that one oughtn't to be complacent about commoner species. Moving on from Tackley, Crecy Hill at the top of the oolite escarpment overlooking the Cherwell valley was a bit of a disappointment, being very scrubby and quite rank. However, the hairy violets (Viola hirta) were flowering, which brings me to what I would say was my find of the day.
Some botanists may regard the identification of hybrids as difficult, esoteric or just pointless. However, I find hybrids fascinating as they confuse our neat taxonomic system that reduces plants to well-defined objects called 'species', adding an extra challenge to recording; hybridisation has also been immensely important in the evolution of plants. I shall therefore always be interested to receive information about possible hybrids in the county. That isn't to say that I will be sufficiently knowledgeable to help in every case where hybridisation is suspected, but the BSBI has plenty of experts who can!
Having taken my time over the violet hybrid I eventually made it down onto the floodplain of the River Cherwell, where squeezed between the escarpment and an expanse of bright green improved grassland in the floodplain is Northbrook Marsh LWS. As this is private land and I am planning to survey the site later in the season I will say no more of the LWS for now.