Tuesday, 21 October 2014

Hunt for hornworts!

A month ago I led a walk up Carn Ingli for a group of horticulture students from Kew - and a mighty friendly group they were!  We saw algae, lichens, liverworts and mosses, and to my great relief stumbled across the 3rd Phylum of bryophytes: the Hornworts (Anthocerotophyta).  There are very few Glamorgan records of Hornworts, but they are pretty frequent in damp stubble fields in Monmouthshire, Carmarthenshire and Pembrokeshire and are surely under-recorded in VC41.

Anthoceros punctatus remains unrecorded in Glamorgan, but it's usually the easiest species to find in Pembs: poached, rushy corners of cattle pastures are the classic locus, although it also grows occasionally on clayey ditch banks or even on lane banks.  Phaeoceros laevis has similar habits but is more regular in arable; the only recent Glamorgan record was Barry's from Staffal Haegr, but there are four 20th century ones as well, albeit not confirmed to species level.  Anthoceros agrestis is locally frequent in damp cereal stubbles in central Monmouthshire, along with Phaeoceros carolinianus, and both could be present in clayey arable somewhere in Glamorgan.

All of the hornworts look like mid/dark green thallose liverworts, and could be ignored as Aneura or Pellia if not fertile.  Look out for the 'horns' or for male 'pits' in the thallus.  Here are a couple of photos to give a search image.

Phaeoceros laevis alongside Riccia glauca in a very mossy stubble field.

Sporulating Anthoceros punctatus on a road verge in Co Cork. 
The spores of Anthoceros are black, whereas those of Phaeoceros are orange.

Please go out and hunt for hornworts soon!


  1. Fascinating...I'll certainly look out for those. I've not done anything on arable yet, but Julian tells me there are some interesting arable margins around Lavernock Point which must be worth a look.

  2. A damp autumn and winter help with arable, as does owning Ron Porleys arable bryo book.

  3. Yes, I might have to invest in that - I was eyeing it up recently.

  4. I have a dim memory of Phaeoceros laevis in the Botanic Gardens on the Swansea University campus, which Quentin Kay showed me (but many years ago). I ought to search for it again!
    One of the many things that is fascinating about hornworts is that they contain nitrogen-fixing colonies of Nostoc, so they may require higher levels of phosphate than other bryophytes, but lower levels of combined nitrogen. Arable land is rich in phosphates (and nitrates), so perhaps that goes some way in explaining their preference for that habitat.

  5. Just found P. carolinianus in my garden! Not so embarrassing as it sounds since the patch was only 'dug' (I'm not a gardener) in March and the patches of hornwort are still small but easily identifiable. That's now the third location of this species in Cardiganshire in the last few weeks. I think the resemblance of the (initially green) horns to grass seedlings is contributing to a general lack of records since if the horns more or less cover the thallus, as they often do, that's all you see from a standing or stooping height.