Thursday, 22 April 2010

PLANT: Cotoneaster induratus, new to Lancashire as a naturally-sown plant

October 17, 2009:
Although in this country Cotoneasters are usually grown as garden plants or for amenity decoration they also often spread into the natural environment when bird sown. This is a result of birds eating the ripe berries, the seed of which passes through them undigested and is later spread into a new habitat via their droppings.

A single magnificent shrub of Cotoneaster induratus was discovered and photographed (above and below) in a semi-natural habitat in a disused limestone quarry near Carnforth. It was laden with bright red berries and was a most attractive sight. Initially there was uncertainty as to its identity until it was confirmed as this species by Mrs Jeanette Fryer. Unfortunately, the quarry is now scheduled for housing development and even though this is the only naturally-grown representative of the species in the county, it is quite likely to be lost soon.

In this species the orbicular bright red fruits are slightly hairy whilst the new leaves and stems are much more so.

Other species of Cotoneaster present at the locality include C. dielsianus, C. horizontalis, C, rehderi and C. simonsii.

Wednesday, 14 April 2010

LICHEN: Peltigera leucophlebia near Haverthwaite, Cumbria

April 13, 2010:
This is a relatively large and quite striking lichen whose thallus is bright green when wet but becomes duller and browner if dried out.

In Britain it is quite local, often found in upland areas usually overgrowing bryophytes on base-rich substrates. However, photographed here it was in old coppiced woodland close to sea-level on small moss-covered limestone boulders.

Cephalodia (large dark spots) can be seen on the surface of the thallus. These contain a cyanobacterium capable of nitrogen fixation but the presence of any fertile apothecia is rare. Other characteristics are the curly (crisped) margins of the lobes of the thallus which has a white underside with black hairy rhizines.

Tightly crisped lobes are well in evidence

The black rhizines show up well against the white underside of the thallus.

I'm grateful to Jeremy Roberts and David Clarke for details of this locality.

Sunday, 11 April 2010

LICHEN: Lobaria virens in Cumbria

April 7, 2008:
A visit to see this interesting lichen. Lobaria virens is an epiphyte which attaches itself to tree bark and whose presence is a classic indicator of ancient woodland. In the British Isles it has a westerly, oceanic distribution and is nowadays mainly found in south-west England, Cumbria, western Scotland, and Ireland. Everywhere however it is scarce or very scarce and is particularly susceptible to atmospheric pollution, especially sulphur dioxide.

It is found on the more acidic-barked trees such as oak and ash. When growing on trees which have become isolated due to woodland felling it may dry out and die off. Lobaria virens also occurs in Scandinavia and in western and southern Europe.

Below, the fruiting bodies (apothecia) can be seen as prominent, slightly concave brown discs.

Below, the small volcano-like protuberances are incipient apothecia which will develop similar to those shown above.

A Cumbrian oak with a large thallus of Lobaria virens. Towards the bottom left of the trunk the related Lobaria pulmonaria can just be seen.

I'm grateful to Mike Porter whose eagle-eye and persistence located the tree and both to him and to Jeremy Roberts for discussions about Lobaria virens.