Headon Warren on the Isle of Wight, Saturday, 14th September 2013

A joint meeting of the WLG with the new Isle of Wight Lichen Group organised by Sheila and Less Street, the original founders of the WLG. The meeting was to look at Headon Warren, a lichen rich heathland on the coast, with a landslip below, which had not been looked at since 1977. It is the largest surviving heathland on the Isle of Wight and has had a rich heathland lichen flora recorded, with over 20 Cladonia species recorded in the past.

Attending from the Island were Sheila and Les Street, Tony Goodrill and Mike Cottril, while from the mainland were Ginnie Copsey, Andy Cross and Neil Sanderson. Andy and Neil had been picked up by the Streets at the Ferry in Yarmouth, but Ginnie had cycled from Yarmouth. We met at 10.30 at a car park on the road near a footpath to Headon Warren at SZ319864. The meeting had been moved back a day from Sunday to avoid the first autumnal storm of the year, with the weather initially sunny but with rain showers threatened.

After walking up the right of way we entered the site from the north, where we started recording in 1 km square SZ3186 (SZ310865), with the croaking of a raven greeting us. Here there was a narrow band of parched acid grassland along the path between dense Bracken, which was mostly too trampled for lichens. Some Cladonia furcata was found on the edges with possible Cladonia ramulosa suggested by the patches small yellowish squamules, which was confirmed by less trampled material up hill.

A Domestic Apple in the scrub was briefly recorded, with beautifully fertile Physcia tenella photographed along with Ramalina farinacea, Xanthoria parietina, Lecidella elaeochroma f. elaeochroma, Ramalina fastigiata, Melanelixia subaurifera, Lecanora confusa, Parmelia sulcata, Parmotrema perlatum and Evernia prunastri. The presence of the latter, a nitrogen hating species, suggested the abundance of nitophiles was due to high pH from sea spray rather than pollution.

Fertile Physcia tenella on Apple

Further up the hill we entered grid square SZ3185 at SZ315 859 and the grassland widened out and the trampling pressure reduced on the grassland, Cladonia furcata increased in cover and then Cladonia portentosa appeared and Cladonia ramulosa proved to be the stood on squamules seen below. Soon we were in a wonderful lichen rich grassland with an abundance of Cladonia cervicornis s. str., frequent Cladonia foliacea along with Hypogymnia physodes and Cladonia rangiformis. The grassland was pitted with old gravel diggings, some of these still had small sand banks, which produced a collection of obscure crusts including the green C + fleeting red Micarea viridileprosa Nb (NS) (new to the IoW), the pale brown sorediate Placynthiella dasaea (new to the IoW) and Placynthiella uliginosa. In addition, Cladonia coniocraea and Cladonia diversa were also added to the list. The acid grassland is clearly heavily grazed by rabbits and is in very good condition. There were a few patches of the invasive exotic moss Campylopus introflexus but these were not obviously a problem; it is mainly a serious issue where ammonia deposition is high.

Acid Grassland

We then moved into heath, here the lichen abundance was reduced where Heather cover was high, but open patches were frequent and a similar assemblage to the acid grassland occurred, with Cladonia foliacea, Cladonia diversa, Cladonia portentosa, Cladonia furcata, Hypogymnia physodes, Cladonia coniocraea and Cladonia rangiformis noted. At SZ3140 8598 possible Cladonia rei was collected and confirmed by the combination of the UV + white fluorescence of the medulla and a Pd + orange reaction. It looks like a somewhat twisted Cladonia subulata but with a more corticate base and the medulla fluoresces. This was new to the Isle of Wight and seemed quite frequent on Headon Warren. Nearby some of the old heather bushes carried interesting epiphytic lichen floras, with Bell Heather Erica cinerea supporting Evernia prunastri, Lecanora confusa, Lecanora symmicta, Melanelixia subaurifera and Flavoparmelia caperata. On Heather Calluna vulgaris a lichen with a farinose sorediate thallus and pale apothecia was collected, this was latter determined as Fellhanera bouteillei (NS), a species typically growing on leaves in humid locations, which was new to the Isle of Wight. The heather also supported Micarea prasina s. lat and Cladonia fimbriata. Such interesting epiphytic assemblages on heathers, especially on Bell Heather, are emerging as a feature of coastal heathland in southern England (see WLG Studland).

Heath and Lichens

Further on a big old gravel pit in the heathland at SZ312 859 added Baeomyces rufus on soil and Rhizocarpon reductum on flint, and more interesting old Bell Heather bushes on the exposed side of the old pit. Very excitingly I found some Caloplaca asserigena Nb (NS) on one of the Erica bushes (SZ3125 8591), then I spotted some more on a Erica branch collected by Sheila for another species and finally, finally an Erica branch ripped off by a hole in my trousers pocket produce yet more. This was new to the Island and was the third record from lowland England. Here it appears to be a specialist of under shrubs on coastal heathland and in saltmarsh (see WLG Studland). It is more widespread on twigs in the uplands. Also new from the pit was Physcia tenella on Erica and Cladonia subulata on the ground.

Lichens in Pit

Out in the Solent we could see a big rain shower which just missing us but it was now windy on the seaward side of the hill. On the summit (SZ312 858) we added Cladonia floerkeana, which was small and rare in this heathland; it is perhapse characteristic of more acidic heaths. Below a wooden rail along the path added Lecanora conizaeoides f. conizaeoides and Micarea denigrata, with Trapeliopsis granulosa in the heath. Over in the sheltered side of the hill we went into another old pit with some more epiphyte supporting Erica cinerea bushes (SZ312 858), with Ramalina fastigiata, Fuscidea lightfootii and Parmelia sulcata new to the substrate. Cladonia squamosa var. subsquamosa was added to the heath list.

We then had lunch in this sheltered pit, after which Hypotrachyna afrorevoluta, Physcia adscendens and Parmotrema perlatum, were added to the list of Erica epiphytes, with Parmelia sulcata also seen on the ground. Trapeliopsis flexuosa was recorded on Calluna lignum and some very large Cladonia foliacea was seen. The latter had squamules over 2cm long so could fall within Cladonia convoluta VU (NR/S41), if this is accepted as a species. A fragment of ironstone supported Trapelia glebulosa. At the base of the pit was the remains of a war time installation (SZ31392 85864), which had left a patch of slightly enriched ground with bits of broken concrete. In this was the odd Cladonia taxa that has been recorded regularly in the south, including two WLG meetings (Beaulieu Heath & Browndown). It has coarse schizidia (flattened corticate granules) in the cup and the upper podetia, a corticate podetia base and large olive-green basal squamules with upturned ends showing a blight white underside. These are often misidentified as Cladonia pocillum, but they are not, and had been provisionally identified as either Cladonia hammeri or Cladonia pulvinella. These, however, are now known to be a single American species Cladonia hammeri, with similar European taxa actually very closely related to, and probably not genetically separated from, Cladonia humilis. For now I am recording them as Cladonia humilis “schizidia form”. Also present on the soil were Peltigera hymenina, typical Cladonia humilis, Collema auriforme and Cetraria muricata. On the concrete were Xanthoria parietina, Xanthoria calcicola, Aspicilia contorta spp. contorta and Verrucaria nigrescens f. nigrescens.

Lunch Pit

We then walked westwards along the ridge, there was a lot of open wind swept heath, but curiously it was rather barren for lichens; in the areas we looked at it was the acid grasslands and old pits in the heathlands that were of high interest. The undisturbed heaths were much less diverse, although most of the pits were probably last work no latter than the 19th century, potentially much earlier. We reached our western point at SZ309 858, where I noted Lepraria incana s.str. on a slump bank (doable by its UV whitish fluorescence). We lack the time to go on to more military ruins or to descend into the marvellous looking slumped heath on the coastal side, so went back east along a different route. Below us, in the Solent, the PS Waverley, the last seagoing passenger carrying paddle steamer in the world, steamed west and I noted Dodder Cuscuta epithymum on Gorse at SZ3105 8589.

View to South & PS Waverley

Along the ridge top east of the summit we found a series of shallow old gravel pits with a different assemblage in their bases including Cladonia ciliata var. tenuis and Cladonia uncialis which had been eluding us until then. The first pit (SZ3116 8589) had what I though might be Cladonia arbuscula, but was actually most likely to be monstrous of Cladonia ciliata var. tenuis, with normal material adjacent, along with Cladonia uncialis and Cetraria muricata. A second pit base (SZ3137 8591) supported Cetraria muricata, Cladonia ciliata var. tenuis, Cladonia uncialis, Cladonia cryptochlorophaea (KC + wine red, C –, new to the Island) and Evernia prunastri, with Cladonia macilenta on that pit bank. Another at SZ3139 8591 had Cladonia uncialis frequent and a fine form of Cladonia portentosa with an intact cortex, giving it a silvery look. This gave thoughts of Cladonia mediterranea but there were too many branches in threes and latter cross sectioning of the podetia produced wall thickness measurements closer to Cladonia portentosa.

Lichens in Shallow Pits

We then headed back to the cars and Andy, Neil and Ollie the dog were dropped off in Yarmouth, where Andy and I had a quick pint before catching the ferry, where Ollie had a good sleep.

Ollie on the Ferry

We had made a good start on a resurvey of Headon Warren, with 55 taxa recorded (see species list), including seven new to the Island, and with a CCP index (Cetraria/Cladonia/Pycnothelia index) score of 20, (high quality heathland lichens sites typically scoring over 15).

Download the KMZ file to view route and waymarks in Google Earth, or view as picture by clicking on link below.

There is still much to do, and another visit looking at the heathland on the landslip below is a must. The Streets have already been back and found good lichen rich areas on the under cliff, with lots of Cladonia gracilis. They also added Cladonia poccillum from mortar on the old fort to the west, along with the common Collema auriforme, Leptogium turgidum and the Nationally Scarce Leptogium tenuissimum, the latter new to the Isle of Wight.