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Rh grows at Cothill in Berks, and P. acutifolius, found in Middlesex and Herts, may yet be found. The broad-leaved cotton grass (Eriophorum latifolium), which grows in Berks, Oxon, Herts and Northants, should be looked for in calcareous bogs ; but these are very sparsely repre- sented in the county. Of the sedges we lack Carex dioica, which is found in all the bordering counties except Middlesex ; C. Bænninghausiana, found in Berks and Herts, and as it is sup- posed to be a hybrid of paniculata with remota it may be found ; C. diandra, which grows in Herts, is not likely to be found, nor is C. elongata, which grows in Berks and Beds, The grass Phleum phalaroides grows in Beds and Herts, and should be well searched for on the Dunstable downs. Agroitis setacea, which grows on the Bagshot Sands in Berks, reaches its eastern limit in that county ; but Calamagrostis lanceolata, which occurs in Northants and Beds, may be found possibly in damp woods. Gastridium, which has been found in Herts, may also be discovered, as it is of rather sporadic growth. Mellca nutans, which I discovered in Bedford Purlieus, Northants, reaches its southern limit in that county. Poa Chaixi occurs in Berks, and is naturalized in Oxfordshire. Glyceria distans is rather of casual occurrence in three or four of the bordering counties. Festuca ambigua has only been reported for Beds. The fern Cystopteris fragilis is reported for Oxon, Herts, Middlesex and Northants, but is probably introduced to each county. The beech fern, limited so far as we know to Berks, where it is very rare. The charad (Tolypella prolifera), found in Northants, Berks and Oxon, may very probably be found, as may T. intricate:, which has been found in Oxon, Beds and Northants, and Nitella mucronata, which has occurred in Berks, Oxon, Middlesex and Beds.

The county is not rich in the number of species, but a mere list of them would be very deceptive to the stranger, since so many of them are very rare, so that over a large extent of its area it is practically fern- less. Even of the list of recorded species two or three are nearly extinct, and others are practically doomed to disappear before long. Its proxi- mity to the metropolis has denuded the best known districts of all but the common forms. The Ouse district is perhaps naturally the poorest, as its stiff, heavy soil, either under pasture or arable, is unfitted for fern growth, yet the moonwort (Botrychium), the adder's tongue (Opbioglossum), the black spleenwort (Asplenium Trichomanes) and the hart's-tongue (Phyllitis or Scolopendrium) have been found in it ; the Ouzel district has the honour of being the only one where Dryopteris or Lastrea Thelypteris grows, and the very local D. uliginosa, if the latter indeed be correctly identified, and it has also the royal fern (Osmunda regalis), the hard fern (Lomaria Spicant) and others. The Thame district has the oak fern (Phegopteris Dryopteris) in one locality close to the Oxfordshire boundary, and Aspidium aculeatum also occurs. The Thames district has the limestone polypody (Phegopteris calcarea) in one place. The rusty-back (Ceterach officinarum) is rather plentiful in one locality, although it has disappeared from Beaconsfield church, a locality given by Parkinson in 1640 and the black spleenwort (Asplenium Adiantum-nigrum), A. Tricbomanes, Osmunda regalis, Dryopteris montana (Lastrea Oreopteris), unless it has been extir- pated, Aspidium angulare, A. aculeatum and Lomaria Spicant also occur.

The Colne district is the one that has suffered most from the ravages of the fern marauder. We have seen that the Asplenium fontanum has disappeared from Amersham church, but the same tale may be told of Lastrea Oreopteris, Aspidium aculeatum, A. angulare and many others. The spleenwort (Asplenium Tricbomanes), Lomaria,Lastrea or Dryopteris dilatata and spinulosa still remain, but the hedges and woods