Scilly exotics

I've enjoyed other recent holiday reports on this blog so I hope you'll indulge me writing another one, from a bit closer to home...

It's a bit of a cliche to say that the Isles of Scilly feel like a world away from mainland Britain, despite being just 28 miles off the end of Cornwall. But after my first visit to the archipelago earlier this month I could hardly disagree with the sentiment. The flora in particular felt very exotic, with the bryophytes being no exception. Many species that are common in South Wales were scarce, as would be expected on a series of small, remote islands. The epiphyte flora in particular seemed impoverished, with most tree trunks being lichen-dominated instead - even Frullania dilatata was somewhat localised. This was adequately compensated for by the plethora of exotic species (liverworts mostly) which are scarce or absent on the mainland, some of which are imports from the Southern Hemisphere and some possibly from the Mediterranean.

The fun started at Lower Moors nature reserve on St Mary's, where I got excited by an extensive yellowy patch of Telaranea murphyae growing by a path to a bird hide (photos below). I thought this liverwort was restricted to Tresco but I later discovered that the population at Lower Moors had been found in 2003. It appears that the taxonomic position of T. murphyae remains somewhat uncertain; it has not been found as a native in the Southern Hemisphere and was described new to science from Tresco, though it may just be a form of T. tetradactyla. A potentially new population was found later in the week by a path near the lifeboat station at Hugh Town (lower photo).

The excitement really started on Tresco, where a flowerbed in the Abbey Gardens was dotted with the lovely rosettes of Riccia crystallina intermingled with numerous Sphaerocarpos plants (photos below). I collected three Sphaerocarpos samples and after a few days incubation each produced mature spores to enable species identification; pleasingly both species were represented with two samples being S. michelii (spore photo bottom left) and one S. texanus (bottom right).

 

Telaranea murphyae was seen in a few locations within the gardens, along with Lophocolea semiteres and L. bispinosa, but was much more abundant along Abbey Drive where extensive yellow sheets of it covered the ground wherever there was shade from trees (upper photos, below). Growing with it was Calyptrochaeta apiculata (lower photos) - in the Britain Isles this Southern Hemisphere species is known only from here and single sites in Sussex and Ireland.

Bulb fields on St Mary's revealed more Sphaerocarpos michelii, Riccia crystallina and a single rosette of Riccia subbifurca (unless it is R. crozalsii - but I don't think so).

Even the small garden of our cottage had a flowerbed with plenty of fruiting Anthoceros punctatus (photo) and a stone covered in Scorpiurium circinatum.

I'm already looking forward to making another visit sometime...