Meeting report of the South East group of the British Bryological Society, 17 April 2016
Part of the estate of the Earls of Arundel in the late medieval period, Bignor Park had several other owners until it was bought by John Hawkins, who was from a Cornish landowning family with mining interests. The current house was built for Hawkins in the 1820s, and the estate and park now contain many features that have developed over the past 250 years.
The site comprises parkland, woodland and farmland, as well as formal gardens, and sits on a low ridge parallel to the South Downs. Of particular interest, and the focus for our visit, is the chalk stream that runs a few hundred metres down the slope from the house.[1] Other parts of the site include Gault Clay and Upper and Lower Greensand.
The visit was a joint meeting of the Southern and South-East groups, led by Tom Ottley, who took us straight to the stream, which we explored for most of the day. The first location included several chalk ‘rocks’, which were partially coated with Hygroamblystegium tenax, and its thick nerve to the end of the leaves was particularly notable.
The same spot on the stream also included the rather pale green Brachythecium rivulare, enabling us to examine the areas of colourless cells in the basal angles of the leaves.
Moving a little upstream, it was the interesting range of epiphytes which occupied us for a good portion of the day. The first noteworthy find was Neckera pumila, with its undulate leaves, and sticking out from an almost horizontal branch right by the stream. Once we’d seen this, it was useful to compare it to N. complanata later in the day.
Neckera pumila
A nearby tree stump right by the stream was home to the rather smart red tones of Bryoerythrophyllum recurvirostrum, which was new for some of the group and which proved to be abundant on many tree bases along this part of the stream. Close by, some Leskea polycarpa was also examined.
Bryoerythrophyllum recurvirostrum
Several ash trees had fine colonies of Leucodon sciuroides which, being fairly dry, clearly presented us with their curved stems and tightly appressed leaves. We also found more Neckera pumila, this time with numerous capsules, a rare occurrence for this species.
The chalk stream
Being beside the stream meant that several of us necessarily got in the water to better observe what was growing along the banks. It was especially useful to be shown Mnium stellare, since it would otherwise have been easy to assume it was M. hornum, were it not for the absence of elongated cells in the leaf margins.
Yet another waterside tree hosted a small acrocarp, which turned out to be Didymodon sinuosus, so it was instructive to see it in a habitat other than on mortar.
Didymodon sinuosus
Exploring the woods gave us the opportunity to compare a number of Orthotrichum species, which was a valuable introduction or revision for some members of the group. In addition to O. affine, we observed the gemmae-laden O. lyellii, the smaller, cute O. pulchellum and frequent patches of O. stramineum, with its distinctive dark reddish-brown tip to the calyptra. Orthotrichum tenellum was occasional, until near the end of the day we found a 2m-long colony of it on a fallen ash.
Orthotrichum stramineum
An exciting find was that of Leptodon smithii, observed in small clusters on trees in a damp part of the wood. One tree in particular sported an especially large colony, though it didn’t make it any easier to photograph. Another tree base was found to have a covering of Anomodon viticulosus, Leucodon sciuroides and Leptodon, so a small party gathered to enjoy all three ‘dons’ in a small space.
Leptodon smithii
Looking at the dons
Within the stream there is a fish ladder, probably constructed in the early nineteenth century when the estate was redesigned. The brickwork along the edge of this structure was fruitful, with Fissidens crassipes forming a narrow band just above the water level along with copious mats of Rhynchostegiella teneriffae a little higher up the sides. Also on the banks nearby were large amounts of Mnium stellare.
Climbing the fish ladder
Rhynchostegiella teneriffae
Deeper into the ash woods Tom looked for some small chalky rocks which he knew to be there, though they were somewhat hard to find now that the entire woodland floor was thickly covered in Ramsons (Allium ursinum). Nevertheless, once located, we were able to find the diminutive Fissidens gracilifolius and the even smaller Seligeria calycina, both fruiting. David Streeter remembered the older name for this tiny moss – Seligeria paucifolia, seemingly more fitting.
Ash and Ramsons
Finally, after sliding down some very slippery banks, our last stop was at the fallen ash with the large Orthotrichum tenellum colony, which also provided us with the chance to study the slender pleurocarp Platygyrium repens which is quite scarce generally and appears to be rather sporadic in occurrence.
The fact that Bignor Park was once owned by John Hawkins gave us a sobering botanical link for the meeting; not only was the previous owner of the estate an accomplished geologist, but was also a keen plant collector, and was elected FRS in 1791. During 1787-1788 he toured extensively through eastern Europe and accompanied John Sibthorp on his tour of Greece, collecting plants. The latter was the son of Humphrey Sibthorp, the Sherardian professor of botany at Oxford, and a much greater botanist than his father; indeed he took over his father’s chair in 1784. Sibthorp and Hawkins made a second visit to Greece in 1795, continuing to gather materials for Sibthorp’s planned flora.[2] However, Sibthorp was ill on the return to England, and died in Bath in 1796.
Hawkins was one of Sibthorp’s executors and was charged with arranging for the completion of the Flora Graeca, which was an enormous task which eventually took forty years to complete, and only 25 sets of the work were produced.[3] The challenges in creating this work provide a clear lesson for all botanical collectors. Not only was Sibthorp’s writing hard to decipher but most samples were not even labelled. Hawkins wrote to James Edward Smith: “As to the want of names I well recollect that he never affixed any to the specimens but seemed to have a perfect knowledge of them and therefore thought it perhaps superfluous.”[4] I trust everyone dutifully labelled all the specimens they collected during the course of our field meeting, and in handwriting that was clear and legible.
Many thanks to Ned Bigham for allowing our visit.
[1] “Bignor Park.” National Heritage List for England. Historic England, June 2000. Web. 15 Apr. 2016. <https://www.historicengland.org.uk/listing/the-list/list-entry/1000273>.
[2] Torrens, H.S. ” Hawkins, John (1761–1841).” Oxford Dictionary of National Biography. 2004. Web. <http://dx.doi.org/10.1093/ref:odnb/12675>.
[3] Sterling, Keir B. “Sibthorp, John (1758–1796).” Oxford Dictionary of National Biography. 2004. Web. <http://dx.doi.org/10.1093/ref:odnb/25509>.
[4] Hawkins, John. Letter to James Edward Smith. 25 June 1799. The Linnean Collections. Linnean Society. Web. 15 Apr. 2016. <http://linnean-online.org/61883/>. Ref: GB-110/JES/COR/5/33.
Diversions in Natural History 