Sunday, 11 January 2015

Andreaea rupestris var. rupestris in RCT

Hilary and I spent an hour in the vicinity of the Ton Pentre overlook (SS939945) near Graig Fach, on a cursory trip to RCT yesterday afternoon. Two under-recorded tetrads (SS99H and SS99M) can be accessed within walking distance here and despite the bitterly cold windy conditions we managed to get numbers up to the albeit  modest totals of 39 and 21 respectively.

Graig Fach

A crippling view of a 'ringtail' hen harrier below the overlook was one of the high points of the day. The other was finding Andreaea rupestris on a number of sandstone slabs in the sheep-grazed moorland.

The leaves of Andreaea rupestris are somewhat falcate-secund with a sheathing base.

Unlike A. rothii, the leaves of A.rupestris don't have a costa and unlike A. mutabilis the basal marginal cells are rectangular. 

Basal cells of leaf

The prominent papillae on the abaxial side of the leaf are a feature of A. rupestris.

Confusion with A. mutabilis (absent from South Wales) is possible, but the leaves of that species lack a sheathing base, have a distinct patch of yellow cells near the base and have basal, marginal cells that are more or less circular (isodiametric). Andreaea alpina is usually a much bigger plant, with leaves that are a different shape, with sinuose basal cells, denticulate basal margins and lack prominent papillae on the abaxial side. 
 A. rupestris is much less common than A. rothii  in South Wales. For example, there were only 3 previous records in the Mapamate database for VC41, all from the vicinity of Craig y Llyn and only one of those (courtesy of  SDSB, BS and GMT from their Craig y Llyn trip last autumn) is recent. However there's a lot more habitat like this to explore in upland Glamorgan, particularly in RCT and Bridgend, so I think we'll be able to put a few more dots on the map in the near future. Among the other mostly unremarkable species we recorded were Racomitrium fasciculare (which is abundant here) and Ptychomitrium polyphyllum - typical species of exposed, acid rock on our moorlands. 


  1. A rupestris is also hard to find in the Beacons - there is a cluster in central Beacons and also the southern limb of the Black Mountains above Crickhowell, with an outlier in a sinkhole on Mynydd Llangatwg not too far from Monmouthshire boundary. I can't recall if Sam has since found A. mutabilis in Carmarthenshire, but several years ago when surveying Allt Rhyd y Groes NNR in N. Carms it turned up on the north bank of the river which forms the boundary between Carms and Ceredigion and therefore as we were recording for the Carms Flora at the time it was in the wrong county!

  2. I assume that the most southerly dot for mutabilis in the new atlas is the population you are talking about Graham. Given that it is likely to be confused with rupestris and therefore probably under recorded, it is definitely worth checking these little Andreaeas carefully

  3. Lovely pic of Graig Fach and a great record

  4. I agree - excellent to have this new site for A rupestris. It is very rare in Monmouthshire, with two known sites (surprisingly far south) in ST29.

    I have not found A mutabilis in VC44 despite looking. There are now 2 or 3 Ceredigion records, including that one from SN74 on the 'wrong' side of the Pysgottwr. It is a pretty distinctive little thing when found, with its leaves widely separate on the stem - I think it's one that you know when you find it. The main problem is that quite a lot of the A rupestris in Wales is intermediate between var rupestris and var papillosa and has much narrower leaves than typical examples; there's a bit more on this in either the Carms or Pembs Flora.

  5. The only time I have knowingly seen mutabils was by the Pysgotwr, so not a lot of experience to draw on, but I seem to recall the plant was a little more lax and stems longer than your average rupestris and it was also growing on a rock that was periodically flushed - the field guide picks out these differences in habitat so this may help with the decision to collect a stem for checking or not.