Umbilicus rupestris
Umbilicus rupestris in U1 grassland

Taxonomy

Synonyms:

  • Umbilicus pendulinus DC.
  • Cotyledon umbilicus-veneris auct.

    • The scientific name comes from the navel-shaped leaves, and its habit of growing on rocks. Its common name is Navelwort.

    Chromosome No.: 2n = 48.

    Distribution

    U. rupestris has a remarkably westerly distribution in Britain, occurring mainly in Wales, the south-west of England, and the Clyde Islands of Scotland. In Ireland it is widespread except in the most inland places and parts of the east coast. Its distribution is presumably largely governed by rainfall and humidity, but it is a lowland plant and it is absent from the north, so temperature may also play a part.

    Although the New Atlas shows U. rupestris as declining slightly, this is not apparent from the Maps Scheme maps, although the data is still too patchy to be sure. If anything, there appears to be an expansion of its range, and whether that is due to deliberate planting or is possibly climate related is not yet apparent.

    Ecology

    The substrate on which it grows is an attribute that seems worthy of investigation. In the Flora of Shropshire (Sinker et al. 1985) it is described as growing on sandstones, siltstones and dolerite, but avoiding limestone and quartzite. Grose (op. cit.), however, says it grows on limestone walls in Wiltshire. In the Floras of Cornwall (French, Murphy & Atkinson 1999) and Dorset (Bowen 2000), it is said to sometimes occur as an epiphyte on trees. Bowen mentions Fraxinus excelsior specifically as the host, although that was based on just one observation.

     

    In Shropshire it grows on rock outcrops in U1 Festuca ovina grassland at Haughmond Hill; in recent W8 Fraxinus excelsior woodland at Earl’s Hill; and in W16 or W17 Quercus petraea woodland at Oaks Wood. The NVC books (Rodwell 1991) only list U1. At Haughmond Hill, plants regrew quickly after a fire in 2005.

    Status

    Origin: native in the west of Britain and in Ireland, but unknown in some parts of the east (see Future work, below).

    Rarity: common.

    Threat: not threatened.

    Conservation: it is not officially on any conservation list, but half a dozen county recorders have listed it as an axiophyte.

    Predators

    The larva of the hoverfly Cheilosia semifasciata mines the leaves of U. rupestris and sometimes causes the collapse of entire plants by the autumn. This invertebrate was considered rare but has turned up in a few new sites recently, and would be worth looking out for. The maps produced by the Hoverfly Recording Scheme show current recording levels.

    This is apparently the only Navelwort leaf miner in Britain, so it is fairly easy to record.

    Cheilosia semifasciata (Nigel Jones)

    > next species

    Go to the Maps Scheme map

     

    Future work

    One unresolved question about this species is its status away from its core populations. The New Atlas (Preston, Pearman & Dines 2002) gives a few red dots in the east, claiming that these are introduced plants. This seems to be based on the assertion in Beckett & Bull’s (1999) Flora of Norfolk that a single plant at Sisland Carr (TM39) may have been planted. The old Fl. Norfolk (Petch & Swann 1968) does not list this species, which adds some weight to that assertion.

    In the Flora of Wiltshire (1957) Donald Grose describes U. rupestris as native or denizen, where a denizen is a plant that has colonised man-made habitats but would not occur otherwise. He mentions just one instance of the plant on a hedgebank; otherwise it was found only on stone walls. Wiltshire is on the edge of its range, and Grose describes how plants in the east of the county are smaller and more sparse.

    The Maps Scheme maps show that U. rupestris is recorded in scattered locations almost throughout the British Isles, from East Kent to Aberdeenshire. It would be worthwhile collecting observations about its origin in these places. If it is deliberately planted, does it persist? Or are these scattered colonies ‘denizens’ or colonists rather than genuine introductions?

    References

    Beckett, G., Bull, A. & Stevenson, R. 1999. A Flora of Norfolk. Privately published.

    Bowen, H. 2000. The Flora of Dorset. Pisces Publications, Berkshire.

    French, C.N., Murphy, R.J. & Atkinson, M.G.C. 1999. Flora of Cornwall. Wheal Seton Press, Camborne.

    Grose, J.D. 1957. The Flora of Wiltshire. Wiltshire Archaeological and Natural History Society, Devizes.

    Petch, C.P. & Swann, E.L. 1968. Flora of Norfolk. Jarrold & Sons Ltd. Norwich.

    Sinker, C.A., Packham, J.R., Trueman, I.C., Oswald, P.H., Perring, F.H. & Prestwood, W.V. 1985. Ecological Flora of the Shropshire Region. Shropshire Trust for Nature Conservation, Shrewsbury.

    Acknowledgements

    Photograph of C. semifasciata by Nigel Jones.

    Citation

    Lockton, A.J. (date accessed). Species account: Umbilicus rupestris. Botanical Society of the British Isles, www.bsbi.org.uk.

    Send us your comments and Feedback

    Martin Rand (19/1/08): In Hampshire, where it's widespread but rather localised, it is overwhelmingly a plant of hedgebanks on fairly acid soils (Tertiaries in the New Forest area where it is locally frequent and sometimes abundant, Upper Greensand in East Hants where it is rare). In these situations it often appears as a "basal epiphyte" usually on oak, growing in among the root buttresses, but I have never seen it growing higher in the air. Francis Rose recorded it on Oak at Brockenhurst (see Flora of Hants).

    Alison Bolton (23/1/08): Although most of the sites around Brockenhurst , in the New Forest, are on banks there are at least two oak trees with U. rupestris up to 8 feet of the ground. One near the Setley entrance to Roydon Woods NR and the other between the A337 and Brockenhurst church on the Tile Barn end of the road.

    Sarah Whild (28/2/08): Umbilicus rupestris is a colonizer of well-tended flower beds at Dale Fort Field Centre in Pembrokeshire (several seedlings seen in February 2008) so it appears to have the capacity to act as an opportunist in areas where it is very common.

    Bruce Gilliland (24/3/2008): In Aberdeenshire it’s found on dry stane dykes primarily made from local granite, near Findon, which is near the sea. Rainfall is typically low since it’s the east coast but Findon is in the Haar belt and does suffer from summer fogs so humidity can be high on occasions. It grows on several dykes, separated by fields and appears to be spreading by natural means. Some plants have been covered over by soil spread by a local farmer, but plenty remains.