Higher Plants of Cwm Rhaeadr

An Introduction to the Survey of Higher Plants made by M & J Iliff 2007

In former times Cwm Rhaeadr would have been part of the Mynydd Mallaen moor, whose side valleys are often sheltered and species rich.

The moorland character is revealed by plants like Blechnum (Hard Fern) which is very frequent, Juncus squarrosus (Heath Rush) and Wahlenbergia (Ivy-leaved Bellflower).

It is noticeable that the common hedgerow plants like the Red Campion and Cow Parsley have not been seen.

We know that more recently there have been many small farms on the site, but hardly a trace of any of these remain in the form of common weeds like Nettles and Docks which can usually be found as evidence of habitation.

The only obvious instance consists of two enormous Box trees and a variety of large-flowered Victorian Daffodils growing not far from the buildings presently used by the scouts (Cwm Rhaeadr barns).

Due to the shading effect of the trees the greater part of the species are to be found, fortunately for the passer-by, on the roadside verges: many of these are very species rich, showing a great variety of composites, vetches, clovers and umbellifers and include in the drier parts, an abundance of the small pink Centaury.

The ditches often have an abundance of Rushes and Sedges and the carpet-forming pink Bog Pimpernel.

Perhaps the most varied area is the riverside path from the bridge to the hairpin bend below the waterfall. Adjacent to the bridge is quite a large colony of the graceful, many-branched Equisitum sylvaticum (Wood Horsetail), only appearing in the summer months. Also alongside the path are to be found Solidago (Golden Rod), Wahlenbergia and large clumps of Politricum (Haircrop Moss).

Much of the variety of plantlife in Cwm Rhaeadr lies in its abundance of Mosses and Liverworts which are fully considered in the parallel survey by Mr Ray Woods.

Download list of Latin, English & Welsh plant names

Plant records

Plant records at Cwm Rhaeadr (SN 757437-766424)

Mary & James Iliff 23.6.01

Conifer plantation open, with considerable space (incl. 2 small meadows) for herbaceous cover. Infestation by Bracken & Rhdodedendron not extensive. Grasses include Cynosurus cristatus (Dog’s Tail), an indicator of old pasture.

Usual wayside herbaceous plants of district well represented; also the choice Wahlenbergia (Ivy-leaved Bellflower) of damp acid habitats, and Marsh Marigold (Caltha; no longer common).Too early in season to determine Docks: these probably Rumex sanguineus and/or obtusifolius. Relics of adjoining moorland include Heather, Bilberry, the sedge, Carex binervis, the ferns Blechnum and Lemon Fern, the Rush Juncus squarrosus, and the graceful Grass Deschampia flexuosa. Filmy Fern (Hymenophullum) was not seen, but is probably present near some stream.

Most choice record perhaps the graceful Wood Horsetail (Equisetum sylvaticum), now quite uncommon due to drainage and loss of old pasture, near 761427. The Horsetail seen.

Sedges and Kushes well represented: 8 of the former, inc. the choice Carex pallescens, and 7 of the latter. Prevalence of the Rush Juncus conglomeratus acid conditions.

Aliens seen: New Zealand Willow-Herb (Epilobium brunnescens), now rapidly invading open gravely acid habitats (e.g. Llyn Brianne), and the Rush J. tenus, now spreading rapidly (sticky seeds) along trackways through footfall and wheeled traffic.

Notable trees: splendid quite untouched relic of old Sessile Oak wood c. 756436-2, and 1 well-grown specimen of Alders Buckthorn (Frangula alnus) at 760435, beside road near tributary stream. The common Alders looked in good condition.

Not possible to monitor Lycopod population thought to be still present on adjacent moorland because of the foot-and-mouth restrictions.

Desirable that future replanting should leave proportion of open space available to allow continuance of present spp. Rhodedendron and Bracken may need some control in future. Latter should not be sprayed because of possible side-effects on rich fern population, the Horsetail, and any adjacent Lycopods.

Total of Gymnosperm and Angiosperm records: 131. In addition, a Hawkweed and a possible Goat Willow/Grey Willow hybrid sent to NMW for determination.

Neither recorder expert on Fungi or Bryophytes. Early in season for former; a Russula seen. Of the latter, the mosses Dicrancum maius, Rhytidiadelphus squarrosus, R. loreus, Thuidium tamariscinum, Plagiothecium undulatum (in oak wood) and Sphagnum and Polytrichum spp., and the very common liverwort Pellea epiphylla were seen.

The complete list spp. recorded available from James Iliff on request.


Cwm Rhaeadr: need for Working Party

During a site visit, Summer 2003, noticed that there is a growing infestation of 2 spp.: Ragwort (Senecio jacobaea) & Rhododendron ( Rhododendron ponticum) . Both, for different reasons, are undesirable. The first is classed as an Agricultural Weed. It is poisonous to horses if more than a certain amount is eaten, and in view of our encouragement to riders its presence is counter-productive. It is not in fact yet a widespread sp. in this area, but the legal position is that landowners are obliged to prevent its spread . The second is well known as an invasive ground-cover sp. in plantations that smothers & ultimately kills all other lower-story spp. by exclusion of light and inability of the leathery leaves to degrade to humus. Its value as winter shelter for small birds must be offset against its undesirable qualities, but it spreads very rapidly and needs strict control.

Although both are technically the landowner’s responsibility, it seems to me that as the managing body in partnership we should address this question because it is doubtful whether FE would carry out control at all thoroughly (and might well do it by weed-killer) and, at the present stage when the infestation is not yet serious, it should be quite easy to take on.

The Ragwort was seen in the verges of the main road down towards the bend of the bridge over the Nant Rhaeadr. This is the kind of situation it seems to favour, and doubtless others of the main FE roads have some as well. The Rhododendron was seen as small seedlings in the gravel of the road forking uphill to the right after the Scout Hut & leading to the SW gate to the Mallaen. It has been able to get established because there is little traffic on this road, but doubtless likewise there are other localities. A first stage might be a day’s outing by a party primarily to search for and mark down places where work is needed; this is a job too much for one person.

Once specimens have been seen, recognition is easy. The Ragwort will be dead at this season, but it forms permanent winter rosettes (like e.g. Foxglove, except that Ragwort is perennial) that have characteristic frilly leaves. It will in any case be helpful for people to learn, because a panic frame of mind in which yellow daisy-like flowers (Composites) are destroyed indiscriminately could be an unfortunate outcome of publicity by the horse lobby that has actually happened in some parts. The Rhododendron seedlings also form rosettes; the leaves are very yellow green & quite untoothed and once seen could not be confused with anything else. They are very easy to uproot by hand. Large plants of the Ragwort are tenaciously rooted and need a garden fork; smaller plants can also be pulled by hand.

The question might be discussed with FE to see if they have any plans to deal with the old established Rhododendron growth. This would need saws, & probably poison injection.


Cwm Rhaeadr: new records, including Mosses

764427: Filago minima (Small Cudweed). Dry stony bank dividing beginning of fork between upper and lower roads. First found by M. & J. Iliff in May, and then not determined: after growing one specimen at Eithin and seeing it develop there is no doubt of its identity, and on a more recent return visit the colony was seen to contain at least 100 plants and probably more.

This small annual member of the huge Daisy family seems to flourish on bare dry ground where there is little competition. It is an insignificant thin grey little plant, branched above, with tiny narrow leaves and small brownish-yellow flower heads. It is said to be “locally common” but has not been seen by us in this county before. The only common Cudweed around here isGnaphalium uliginosum (Marsh Cudweed), which does like it damp, but occurs in later summer in all older pastures, often on bare spots; it is a low-growing silvery-grey annual with untidy-looking narrow leaves. It is often in field gateways, with Pineapple Weed and Toad Rush; like these, the seeds are probably carried on tractor wheels.

763429: Anagallis tenella (Bog Pimpernel). Found by Angela Yardley, of Rhandirmwyn, beside footpath descending to left of upper main road, 25.6.04; not recognised, and brought for indentification.

This attractive little pink flower (related to Scarlet Pimpernel) is common round here in flushes and other wet places. It has not been recorded for Cwm Rhaeadr before, but its presence is entirely consistent with the way the site shares the flora of the Mallaen moor. It was said to be not far from a tributary stream, and to form quite a large patch, doubtless in an area that is damp.

Mosses and Liverworts . Enclosed are lists made by Graham Motley, CCW Bryological specialist based at Abergavenny, recording a field meeting of members of the British Bryological Society at Cwm Rhaeadr two years ago. Mr. Motley notes that the area below the waterfall is particularly rich in spp., as was already presumed, but does not think the proposed development in general would be at all harmful; indeed it might have a good effect. His remarks in a covering note are of interest:

Most records come from the waterfall area. This is the most sensitive area, but appears to be unaffected by the scheme. A few locally interesting bryophytes can be found on the track bed itself (often towards the edges) including Archidium alternifolium and Bryum alpinum. These spp. like relatively open ground and so some disturbance from time to time (such as cycling or creating new tracks) would be beneficial. Similarly the nationally scarce Diplophyllum obtusifolium (actually not that scarce in Carms.) likes crumbling banks by forestry tracks and will not be affected by the scheme.

There are two lists: one for the waterfall area, one for the plantation as a whole. This is a very specialised study often needing the microscope for confirmation of distinctions. The Liverworts (the more primitive of the two groups, with a different spore-producing structure) are often very small, and particularly difficult.

A few mosses are very common and easily recognisable and could be shown on display boards. Rhytidiadelphus squarrosus is the plant with little upstanding fingers that is in everyone’s lawn. R. loreus, closely related but looking different, makes firm cushions containing quite strong stems and can be felt to be substantial under the palm of the hand. Thuidium tamariscinum (presumably thought to look like Tamarix foliage), has elegant regularly spreading feathery shoots; it is ubiquitous and extends even into quite deep shade under conifers. Pleurozium schreberi (I wonder who Herr Schreber was, to have a moss named after him!) is the rather untidily branched pale yellowish plant that is all over the Mallaen amongst the grass and bilberries: it thrives in open well-lit quite dryish situations and detached bits may be found anywhere on the grass pulled out be the sheep. It occurs as one of the moorland components of the Cwm Rhaeadr flora. Polytrichum commune forms large dark green cushions often several inches deep, easily seen to be made of individual upright leafy stems like minute fir trees; the leaves are the most obvious of any moss, narrow, pointed, and radiating regularly all up the stem. It likes damp; there are good colonies around the ditch beside the path running N. along the W. side of the stream from the footbridge. On the moor it may be seen at a distance as forming dark green patches sometimes several yards across that are a sure sign of a boggy area. There are other Polytrichum spp., some smaller, but all with the same habit, that are difficult to tell apart. Sphagnum is well known as the most water-loving moss and is found in the ditch beside the same streamside path; in fact there are some 20 closely similar spp., and the locations of the five listed for the site are not stated. Dicranum scoparium, though not occurring in the same quantity as e.g. Thuidium, is easy to recognise: an olive-green little plant with tufts of very fine leaves at the tips of the stems ending in threadlike points and all curving one way, as if the tuft had been combed. It can grow in quite dry situations like grassy banks or dead tree stumps. Rhizomnium punctatum, less common but very distinctive, needs wet, but can grow in comparatively dim light; it occurs in a spring beside the road near the Scout hut. It forms tiny individual upright stems each with a few leaves that are very large in proportion and almost round, and have a pearly sheen.

One Liverwort, Pellia epiphylla , occurs on any damp bare bank but though so common is probably unnoticed. It forms a dull dark green crust on bare damp earth; for a brief season in Spring the spore capsules, like tiny white palm trees, appear in great quantity and are conspicuous. Plagiochila porelloides has a totally different, more moss-like habit, with two rows of close-set rounded little leaves lying flat on the opposite sides of the shoot. It was recorded for the waterfall area, but was seen by JI in some quantity on the other side of the main road, along the footpath from the northernmost hairpin bend to the Scout hut.

Copies of Graham Motley’s two lists (made on different dates) are given below.


British Bryological Society Excursion to Nant y Rhaeadr (Craig y Rhaeadr and Waterfall) (SN 7543) 4th July 2002

Most records from riverbanks, adjacent oak woodland and crags. A reasonably rich site, with the three humidity-demanding Plachiochila species, P. spinulosa, P. bifaria & P. punctata. H.H. Knight recorded the scarce moss Oedipodium griffithianum on crags in this area in the early part of 20th Century (the only other Carmarthenshire site for this species is near Llyn y Fan Fach).


  • Amphidium mougeotii
  • Andrea rothii ssp. falcata
  • Atrichum undulatum var. undulatum
  • Aulacomnium palustre
  • Bartramia pomiformis
  • Brachythecium plumosum
  • Breutelia chrysocoma
  • Bryum alpinum
  • pseudotriquetrum var. pseudotriquetrum
  • Calliergonella cuspidata
  • Campylopus atrovirens var. atrovirens
  • flexuosus
  • pyriformis var. pyriformis
  • Cynodontium bruntonii
  • Dichodontium sp.
  • Dicranella heteromalla
  • palustris
  • rufescens
  • Dicranoweisia cirrata
  • Dicranum majus
  • scoparium
  • Didymodon fallax
  • Diphyscium foliosum
  • Eurynchium praelongum
  • striatum
  • Fissidens adianthoides
  • celticus
  • osmundoides
  • Heterocladium heteropterum var. heteropterum
  • Homalothecium sericeum
  • Hookeria lucens
  • Hylocomium splendens
  • Hyocomium [sic] armoricum
  • Hypnum andoi
  • cupressiforme
  • Hypnum jutlandicum
  • Isothecium myosuroides var. myosuroides
  • Mnium hornum
  • Neckera complanata
  • Oligotrichum hercynicum
  • Philonotis fontana
  • Plagiothecium succulentum
  • undulatum
  • Pleurozium schreberi
  • Pogonatum aloides
  • urnigerum
  • Pohlia elongata ssp. elongata var. elongata
  • Polytrichum commune var. commune
  • formosum
  • piliferum
  • Pseudotaxiphyllum elegans
  • Racomitrium aciculare
  • affine
  • aquaticum
  • fasciculare
  • heterostichum
  • " lanuginosum
  • Rhabdoweisia fugax
  • Rhizomnium punctatum
  • Rhytodiadelphus loreus
  • squarrosus
  • Sphagnum denticulatum
  • palustre var. palustre
  • quinquefarium
  • subnitens var. subnitens
  • Tetraphis pellucida
  • Thamnobryum alopecurum
  • Thuidium tamariscinum
  • Trichostomum tenuirostre var. tenuirostre
  • Ulota bruchii


  • Aneura pinguis
  • Barbilophozia floerkei
  • Calypogeia arguta
  • fissa
  • muelleriana
  • Cephalozia bicuspidata
  • Chiloscyphus pallescens
  • Conocephalum conicum
  • Diplophyllum albicans
  • obtusifolium
  • Frullania dilatata
  • tamarisci
  • Jungermannia gracillima
  • hyalina
  • Lejeunea lamacerina
  • Lepidozia reptans
  • Lophocolea bidentata
  • Lophozia ventricosa var. silvicola
  • Marsupella emarginata var. aquatica
  • Marsupella emarginata var. emarginata
  • Metzgeria conjugata
  • furcata
  • temperata
  • Nardia scalaris
  • Nowellia curvifolia
  • Pellia epiphylla
  • Plagiochila bifaria (= P. killarniensis)
  • porelloides
  • punctata
  • spinulosa
  • Ptilidium ciliare
  • Radula complanata
  • Riccardia multifida
  • Saccogyna viticulosa
  • Scapania compacta
  • gracilis
  • nemorea
  • undulata


British Bryological Society Excursion – Cwm y Rhaeadr Forestry Block centred on SN 762428, July 2002.

Most records are from edges of the tracks, eroding trackside banks, rotting logs under conifers and grassy banks. An interesting suite of species occurs along the edges of the tracks themselves. Most of the species here require open ground and therefore an increase in numbers of cyclists would probably be beneficial.


  • Archidium alternifolium – forestry tracks
  • Atrichum undulatum
  • Barbula unguiculata
  • Brachythecium rutabulum
  • Bryum alpinum – forestry tracks
  • bicolor
  • Calliergonella cuspidata
  • Campylopus introflexus
  • Ceratodon purpureus
  • Cirriphyllum piliferum
  • Dicranella heteromalla
  • palustris
  • Dicranella varia
  • Dicranum majus
  • scoparium
  • Didymodon fallax
  • Eurynchium praelongum
  • hians
  • striatum
  • Hypnum andoi
  • jutlandicum
  • Philonotis fontana
  • Plagiothecium curvifolium – under conifers
  • Pleurozium schreberi [cf. Mynydd Mallaen adjacent – J.I.]
  • Pogonatum aloides
  • urnigerum
  • Pohlia annotina
  • wahlenbergii
  • Polytrichum commune [cf. moorland J.I.]
  • formosum
  • juniperinum
  • Racomitrium aciculare
  • Rhytidiadelphus loreus
  • Rhytidiadelphus squarrosus
  • triquetrus
  • Scleropodium purum
  • Sphagnum denticulatum
  • fallax
  • fimbriatum
  • Thuidium tamariscinum [very common J.I.]
  • Ulota bruchii


  • Cephaloziella divaricata
  • Diplophyllum albicans
  • Obtusifolium (Nationally scarce but under-recorded) – scattered colonies on friable banks by tracks
  • Frullania dilatata
  • Jungermannia gracillima
  • Lophocolea bidentata
  • heterophylla
  • Nowellia curvifolia
  • Pellia neesiana
  • Scapania irrigua – forest tracks
  • nemorea
  • Ulota crispa [? This name is cited as given but must be in error: Ulota is a Moss genus and the name should presumably conclude the above Moss list – J.I.]