The Backs field studies 2011

The Backs.   The 2011 CNHS study area was the Cambridge Backs, which for the purposes of the study included the area within TL4458 roughly between Grange Road to the West, Kings Parade to the East, Magdalene Bridge to the north and Silver Street Bridge to the South.  It is shown on this plan from Where’s the Path?

It was a very dry year, and we only once suffered a shower. 

January 1.  Jonathan, Monica and Steve met on Silver Street bridge, for what has become the traditional CNHS start to the year.  The snow and ice of December had gone, but spells of drizzle rather dampened us at times.  We began by noting the flora outside Queen’s, spotting the distinctive leaves of Milk Thistle Sylibium marianum growing up against a wall. Proceeding clockwise round the Backs, we noted a dead fish on top of the ice that remained in one of the ditches, but it was too far gone to identify the species.  The cobbles on the roadside of Northampton Street sported some Erophila verna that was already just coming into flower, but we pressed on quickly as a pub lunch beckoned.  After lunch we continued along St John’s Street, finding that the Pteris cretica was still present in the grating outside Michaelhouse.  We failed to find any Wall Rue Asplenium ruta-muraria on the steps of the Senate House, although Jonathan did find some later in Silver Street.  Crossing the Garrett Hostel Lane causeway we noted the luxuriant growths of Hart’s-tounge Fern Phylitis scolopodendron and Jonathan spotted a liverwort growing near the water-line.  Deciding that this needed a closer look he leant through the railings and managed to retrieve a sample of Great Scented Liverwort Conocephalum conicum, a relatively scarce liverwort which had not previously been reported from here, the only other extant city site being the Botanic Gardens.  Continuing along Burrell’s Walk and back via West Road we inspected a field that warned us that spikes were not allowed.  As we weren’t wearing any we had a wander round, finding several meadow species that had probably been introduced to a bank separating what used to be tennis courts.  On the homeward walk Jonathan stopped by St Botolphs church, and finding the verger in the church managed to get a quick look round the otherwise locked churchyard, but it was getting dark so more had to wait for another day.  Altogether we saw 145 plant species, along with 6 liverworts, ten mosses and several birds.

February 5. An extra visit was arranged by the Cambridge Lichen group to study the lichens of the area, and to see how they had changed since an earlier study in the 1960s.  Very little of the previously abundant species on Silver Street Bridge remained, but a large number of other species had moved in, reflecting the decline in sulphur emissions and hence cleaner air.  We then moved on to St Benet’s churchyard, a relatively small oasis in the city centre, which had a surprising 40 species in it.  Moving to another previously survey location we looked at King’s Bridge and concluded by looking at some of the trees on the Backs.

February 20.  The main February study took place on a cold and grey February day, although apart from a little early morning drizzle it remained dry.  Before the start Jonathan located the Polypody growing in Free School Lane, which had earlier been discovered by Alan Leslie.  Moving on to Garrett Hostel Lane Bridge, Jonathan and Monica headed towards the Backs, studying several of the Crocus and deciding that there were at least three species present.  A circuit of St John’s playing field revealed little of great interest, though we did see a grey squirrel racing for cover.  The brook did however have a second snowdrop (G. plicatus), and what we at first took to be Gunnera.  Finding more basal leaves on the other side, Jonathan identified it as Giant Hogweed Heracleum mantegazzianum.  After a relaxed lunch we detoured through Trinity, finding Slender Speedwell Veronica filiformis in one of the courts, before arriving back at the meeting point for the afternoon.  Joined by Elizabeth we headed for the Backs, this time heading towards Queens.  Clare managed to locate the group, who she said stood out a mile with books and lenses in hand, and a little later we were joined by David!  On the bank we found a third snowdrop, this time the hybrid of G. nivialis and G. plicatus.  On Queen’s wall we discovered that the plant we had previous called Forsythia, was actually Winter Jasmine, confirmed when we later found both together outside the University Library – Jasmine has six petals, whilst Forsythia only four.  David identified a few birds for the list, including Long-tailed Tit and Robin.  We turned towards the University Library, finding a puzzling bedstraw, which might be Field Madder – we will have to return.  Wandering round the back we found a new bank, verges and another Polypody.  By now it was getting darker so we headed back via Clare, finding Wall Rue and Maidenhair Spleenwort by the west gate before departing our separate ways.

March 20.  March had so far had little rain, and following a preceding sunny day the Sunday was mostly overcast with occasional sunny intervals.  The morning group had been given permission to wander round Queens’ “Grove”.  Here we found a mix of planted and “wild” species, most were relatively common.  Early Meadow-grass Poa infirma was present on the path under trees, and a Bay Laurel Laurus nobilis had seeded under a Birch.  There were a large number of planted and naturalised bulbs, with at least four different species of Scilla, a genus which now includes Chionodoxa.  After lunch at the Mitre, Jonathan and Monica checked the Urtica membranacea that grows outside the Isaac Newton before returning to Magdalene Bridge.  Here we were joined by Deborah, and rather later by Kate and eventually by David Seilly.  Our path took us through Magdalene and St Johns, then through the University Library and Sidgwick Site (and part of Selwyn), returning to the centre of town through Kings.  We found an interesting gall on the catkins of a Weeping Willow Salix x sepulcralis in Magdalene.  In St Johns we found the Goldilocks Buttercup Ranunculus auricomus just coming into flower, and it was also present on the Backs.  Just outside the college gate we found another small patch of Ransoms Allium ursinum, to add to the one found earlier by David Barden on the Backs near Queens.  A surprise find in the Sidgwick Site was Ivy Broomrape Orobanche hederae growing in a corner of an ornamental bed of Irish Ivy Hedera hibernica.  We saw a couple of early Bumble-bees Bombus terrestris, but no butterflies, and added a few birds to the list.

April 17.  The long dry spell continued, and conditions were broadly warm and sunny, though cloud increased after lunch and it became cooler late in the day.  We had permission to visit Clare College, and the morning party began by studying the older part of the College.  The lawn next to Old Schools provided several additions to the botanical list, including many Scaly Male Fern Dryopteris affinis growing at the base of the east facing wall.  First Court was covered quite quickly, but the Scholars Garden took more time, particularly the old boundary wall between Clare and Kings, which had many plants growing on the top.  Most were too far out of reach, though Fern Grass Catapodium rigidum was clearly visible.  Moving across the river to the Fellows Garden we found a host of interesting plants.  Notable was the southern margin, where several Primula and Fritillaria species had been introduced and established themselves and where the uncut grass gave an opportunity for Field Wood-rush to survive.  The brickwork surrounding the central sunken pond provided a foothold for several self seeded garden plants, with the liverwort Pellia endivifolia finding a suitable habitat at the damp base.  By this time we had to break for lunch, and then joined the rest of the party at Silver Street Bridge.  Moving round Queens’ to the Backs proper, we spotted a large fly, which the FSC key allowed us to identify as an Alder Fly, further research later identifying it specifically as Sialis lutaria.  Spiders lurked in the bankside vegetation, and the FSC guide suggested one as the Labyrinth Spider Agelena labyrintha.  We paid a further quick visit to Clare Fellows Garden, then crossed the road to Memorial Court.  Of interest here was the Great Wood Rush Luzula sylvatica rapidly propagating from garden introductions.  It won’t be long before it escapes from the College boundaries.  The lawn in front of Memorial Court lies on the slope of the first Cam terrace gravels and had quite a varied flora hidden within it, including more Luzula campestris, along with Ladies Bedstraw Galium verum.  A particularly sandy bed along the northern drive had several less frequent plants (for Cambridge) including Early Forget-me-not Myosotis ramoissima and Hare’s Foot Clover Trifolium arvense.

May 19.  There had still been no significant rain and the first of our evening visits enjoyed fine weather.  We had permission to visit Trinity College, so proceeded relatively quickly from the Garrett Hostel Lane bridge meeting point to Burrells Field.  Here a friendly porter gave us a swipe card to allow access to the grounds.  We meandered our way into an enchanting mix of formal and informal gardens, beginning with a small area near Bin Brook, where we puzzled over some Comfrey, deciding that the white flowered plant was in fact Russian Comfrey Symphytum x uplandicum, rather than the Common Comfrey S. officinale.  Here we also found Ransoms Allium ursinum, though we have now found this generally rare for Cambridgeshire plant fairly widely in the study area.  Moving on we came to an area of mixed lawn and meadow, where we found indicator plants of neutral to calcareous grassland such as Quaking Grass Briza media, Hoary Plantain Plantago media and Rough Hawkbit Leontodon hispidus.  We also found some rather gone over Goldilocks Buttercup Ranunculus auricomus.   Returning in fading light we found another small area with a meadow surrounded by planted beds.  Some, such as Two-flowered Pea Lathryus grandiflorum and Throrow-wax Buplerium rotundifolium, had clearly escaped and become established in the meadow.  Returning the card, the porter asked if we’d seen the Badgers Meles meles, though had to confess that whilst we’d seen occasional scratching, we hadn’t linked these to the animal.  Those remaining at the end went on to discuss the visit in the Baron of Beef (as the Mitre was closed for redecorating).

June 23.  The drought had broken, with 40mm of rain in the month, and showers earlier in the day, though we were lucky to have a fine evening.  A large party assembled at Magdalene Bridge and we first headed for St Clements churchyard.  Here we found a willowherb and showed how to use a key to identify it.  This lead us to Hoary willowherb Epilobium parviflora on account of its crossed stigma and small flower size, however the plant looked nothing like this, so we suspected a hybrid.  We identified several other plants, then spotted a Harlequin ladybird on nettles, then lots more, mostly of the form succinea, but also a few of the two red spotted varieties.  A grassy bank gave us more debate in identifying a Ground hopper, and a Pill woodlouse.  Moving on we viewed the Pteris cretica at Michaelhouse, then the Yellow strawberry in Gt St Mary’s.  St Edwards had some giant Phytolacca seeding throughout the churchyard.  Passing St Benets we noted the remnant of the University Botanic Garden on Free School Lane and the Polypody growing from a drainpipe.  We had to be content to peer over the wall of St Botolphs as the churchyard is normally closed.  We continued round the Backs, admiring a Swan Cygnus olor with cygnets in Queens’ drain.  Progress speeded up as it grew darker, but enough light remained to identify a Fescue growing near the road, before we continued on to the Mitre for a drink.

July 21.  Our final evening excursion was a punt trip along the Cam.  Cool showery weather had prevailed for a while, and although it was still cool, the showers had gone.  A Magdalene punt was available for the trip, with Clarke providing the punting.  Jonathan navigating, and Monica, Willa and John enjoying the river.  We first investigated St John’s punt pool and tried going down the Brook, but went aground in mud and were then ticked off by the College porters.  Thereafter we kept to the main river bank, travelling just beyond Silver Street bridge and reversing from time to time when interesting things were spotted.  Rather few plants were added to our list, the most interesting being a yellow flowered Clematis Clematis tangutica growing on stonework by St Johns, the most surprising being Meadow Barley growing on a Trinity lawn by the River with the others being common aquatics.  The commonest plants seen on walls were Pellitory of the Wall, Ivy-leaved Toadflax, Gypsywort and Skullcap, the last showing its striking blue flowers.  Perhaps because of the cold, few insects were noted.  We did see fish, but failed to identify any species.

August 28.  The party met at Garret Hostel Lane Bridge, with the plan of taking part in the Opal “Bugs Count” survey.  Our first stop was the “meadow” area of the Backs behind Queens.   Here we investigated “bugs in soft ground surfaces”, which included short grass, under tree self-watering jackets (full of earwigs) and under stones.  Woodlice headed the count, but we did see one of the “Species Quest” bugs – a Devil’s Coach Horse.  We then moved on towards the Sidgwick Site to do “bugs on human-made hard surfaces”.  As expected this was quite a sterile environment, with a grand total of 16 bugs, of which the majority were spiders or harvestmen.  One of the harvestmen was on a wood shingle fence, and its posture helped identify it as ??  Our final hunt was in the meadow of Trinity Fellows Garden, though a short shower drove many bugs into hiding.  In this environment beetles (mostly ladybirds) topped the list, closely followed by grasshoppers.  This concluded the main part of the day, but Monica and Jonathan paid a visit to St John’s playing field and found much of interest around the new tennis courts.  Here the ground had been recently turned over, so many “weeds” had appeared.  Heading towards the rubbish dump Monica spotted a small trefoil, and on bending towards it Jonathan spotted something even more interesting – a delicate looking bedstraw Galium parisiensis.  This is quite a rare Cambridgeshire plant, but it turned out not to be new for the monad, having been seen near the music school on West Road in 19xx.

September 25.  The CNHS party met at Magdalene Bridge on a fine September afternoon and then proceeded towards St John’s College playing fields.  Here we followed two of the Opal surveys, looking at lichens on trees to measure air quality and a hedge for biodiversity.  We looked at four lime trees in detail, finding abundant nitrogen loving lichens on the trunks.  We also saw several ladybird pupa cases, some harvestmen and some rather odd looking pupa cases that we couldn’t identify.  We circumnavigated the new tennis courts, though some of the interesting “weeds” had been mown.  Many seeded goosefoot Chenopodium polyspermum puzzled some of the party, as it didn’t look anything like its illustration in Monica’s book.  A rather down large leaved plant on the rubbish dump was not identified, so Steve took a specimen home to grow it on.  Moving towards the north hedge, we decided not to survey the section behind the football goal, and settled on a 3m stretch a little further on.  Jonathan had brought along a city refuse bag, as it was about a metre long and white – ideal for collecting insects.  This was laid out at the bottom of the hedge, which was then beaten by kicking it.  A deluge of life dropped onto the bag, with spiders of various sizes being the dominant life form, followed by woodlice.  We then moved to Trinity Fellows Garden, and although we didn’t survey the trees, did not that it was much more protected than the playing fields and had several “intermediate” lichens that we hadn’t seen earlier.  One beech had a Velvet mite, which was inspected with various hand lenses.  Leaving through the Queen’s Road gate we had a little foray along Queen’s ditch, though didn’t spot any Marsh Thistle, which had been reported from here in the 1960s.  The party then returned to the centre of town through Clare, before going their separate ways.

October 29.  The long period of drought had continued, with only 15mm of rain in October, about a quarter of the normal total for the month, and with only 60% of the normal total having fallen during the year.  The very dry ground made the prospects of finding fungi poor, and this proved to be the case.  Starting from Silver Street Bridge, the first stop for our team of seven was the area of Queen’s Green.  A couple of stumps had bracket fungi, the largest being a Lumpy Bracket Pseudotrametes gibbosa over a metre across.  On a much smaller scale we noted that many plants were covered with mildew, and as these are generally specific to the host were able to name Cow Parsley, Plantain, Daisy and Hedge Garlic mildews.  A conker here showed a blue mould, and we also found one with a pink mould later in the afternoon.  The mildewed daisy was also being attacked by a rust.  Moving northwards along the Backs we found a troop of Common Ink Cap Coprinus atramentarius growing on the remnant stump of a long felled tree.  Crossing the road to the corner of St John’s playing fields we found our most fungal rich area of the afternoon.  Here amongst others we found a couple of Field Mushrooms Agaricus campestris, and nearby the very similar, but staining faintly yellow, Horse Mushroom Agaricus arvensis.  Amongst the garden rubbish a tree trunk was coloured purple by Silverleaf Fungus Chondrostereum purpureum. Time was passing so we headed to Trinity Fellows Garden to see if the ancient grassland of the meadow had any waxcaps.  Sadly the dry conditions meant that we found virtually nothing here, but just as we were departing Wesley spotted a troop of Clustered Brittlestem Psathyrella multipedata on a steep lawn bank.

November 20.  We enjoyed another fine day and a group of ten CNHS and BBS members assembled on Garret Hostel Lane Bridge.  The number was just on the limit for us to visit as a group the college gardens that are not normally accessible and I set the challenge of adding to the list of six liverworts already found.  We began with Clare, where we had permission to view the Scholars and Fellows gardens.  Altogether we found 41 species of bryophyte, with Leptobarbula berica, found growing at the base of a brick wall on the NW side of Clare Bridge being notable as the 5th county record for the species.  A willow also had a tiny scrap of Radula complanata, making the first of three additions to the liverwort list.  After lunch we moved on to Trinity Fellows garden, where we made a preliminary count of 43 species, and another liverwort addition, Lophocolea heterophylla.  Keen to complete the three colleges that we had permission to visit, we pressed on towards St John’s, though briefly stopped to admire the band of Conocephalum conicum along the river brickwork on Garret Hostel Lane, and rather longer outside Gt St Mary’s whilst several members of the party admired the facilities.  At St John’s the Porters didn’t have a key for us, but kindly agreed to come and open the gate to the Wilderness part of the Fellows’ Garden.  Here we found another two rare mosses: Rhynchostegiella curviseta (which is also present in Little St Mary’s) and R. litorea which were on a steep earth bank above Bin Brook.  Jonathan found Frulania dilatata on an Italian Alder, giving 9 liverwort records for the monad, which approaches being one of the most productive in the county. We also admired a clump of Honey Fungus, though the college gardeners might have other thoughts.  Although getting darker we continued round the more formal part of the Fellows’ Garden and ended the tour with 42 species for the college.