Caerau Road Cutting ST135748

Every time I head into Cardiff on the western access road I tell myself, one day I must stop and look at the road cutting flora. The sparse vascular plant cover and abundant bryophytes on the eroding banks always looks promising. Yesterday I was nearby with a spare couple of hours, so I parked in Caerau and climbed over the fence.

For ref the BGS website shows the geology to be a combination of Blue Anchor Formation and Mercia Mudstone Group, these Triassic deposits exposed by the A4232 cutting. The lack of any top dressing has allowed an interesting assemblage of 26+ terricolous species to colonise. Hypnum cupressiforme var. lacunosum, Ctenidium molluscum (only on the S.E. side of the road) Fissidens adianthoides and Trichostomum crispulum were all abundant, with other frequent species noted including Aloina aloides, Dicranella varia, Didymodon acutus, Didymodon ferrugineus and Homalothecium lutescens.

Didymodon acutus

Didymodon ferrugineus

Didymodon ferrugineus

The central reservation and verge 'dirt zone' held locally abundant Didymodon australasiae and occasional Weissia controversa var. densifolia was noted under the crash barriers.

Didymodon australasiae

Brownfield slack surprise

On my way out to Witford yesterday it was spitting and looking very threatening, so I decided to make a pit stop in an area of the old BP works where I'd previously recorded the vascular plants several years back and have been meaning to return to check for bryos. The substrate is pure furnace slag that floods in the winter and consequently supports rather nice dune slack vegetation with elements of the NVC communities SD13-SD14.

The main bryos in the winter-wet areas were Drepanocladus aduncus and Hymenostylium recurvirostrum var. recurvirostrum, with locally frequent Calliergonella cuspidata, D. polygamus, Didymodon tophaceus, Cratoneuron filicinum, Bryum pseudotriquetrum & Fissidens adianthoides. I didn't have long, but in the area I walked over, I estimated the Hymenostylium colony extended to at least 1500m² (centred at SS74069208) being frequent throughout. There are similar areas in this part of the site I didn't look at, so the colony could be even bigger. Hymenostylium is not something I was expecting in this situation, but I read in the atlas that it grows at mine sites in Cornwall, so perhaps isn't too much out of context. Unfortunately, there's an inevitability this area will be redeveloped at some point, such is the nature of brown field land. [I'm pretty busy at present, but I'll add some microscope pics and better macro shots when I get a chance]

In the evening, on the way back through the site, I rechecked the general area where I saw the Tortella inclinata last month and discovered it also forms an extensive colony, being locally dominant in an area at least 40m x 4m. The main part of the colony is on tarmac, where it grows as mono-specific stands (actually discernable on the Google aerials SS73189138). Here the colony appears to be spreading over the tarmac from the edges, presumably extending by trapping wind-blown sand and gritty slag. Off the tarmac, in adjacent areas of coarser gravelly slag, the species grows as clumps in a more diverse mosaic of short dune vegetation.

Other tarmac colonists with burgeoning populations thriving on these abandoned roads, noted whilst driving across the site yesterday, included Drepanocladus aduncus (photo 1 below) and Didymodon ferrugineus (photo 3 below). The Drepanocladus hosted a fungus, which I have a specimen of - I don't know if Charles is able to point me in the right direction, if so I'll try and key it out?

Mynydd Lliw

SN599019, the search restricted to the yellow areas

At just over 40m a.s.l., Mynydd Lliw is hardy mountainous, nor is it very natural, most of the substrate comprising restored colliery spoil. I've done very little bryologising this week, so I took Alfie out for an hour this afternoon to a part of this site I've not been to before - an area that looked interesting on the aerial images. Following today's downpours, the mosses were luxuriant and it turned out that the brown areas on the aerials were concrete bases dominated by a deep cushion of Didymodon ferrugineus, with some patches of cf. D. rigidulus (both species shown together below).

Of the 26 species noted growing on a thin crust of detritus over the concrete, others of interest included - in decreasing abundance - Trichostumum crispulum, Bryoerythrophyllum ferruginascens, Calliergonella lindbergii, Riccia glauca, R. sorocarpa and Tortula modica.

Mynydd Aberdare

A short stop in the falling snow on the west side of Mynydd Aberdare today added 40-45 species to SO00C & SO00D. The area I looked at was a mixed Larch/Pine plantation with plenty calcicoles along the verges. Didymodon ferrugineus (first two photos) was locally frequent and was found growing alongside both fallax and insulanus, the differences then being quite obvious. Other associates included Calliergonella lindbergii, Ditrichum gracile, Encalypta streptocarpa, etc.

The branches of the Japanese Larches were heavily clothed in epiphytes, including a few patches of Sanionia uncinata (also noted on the track edge at one spot), but the oddest species noted growing on a branch just above head height was Racomitrium ericoides! Has anyone else ever seen this up a tree before? I’ve also retained a reddish-looking Ulota ‘crispa’ with somewhat intermediate characters.

Sanionia uncinata clumps on lower twigs

Racomitrium ericoides up a tree!