Liverworts and Their Phytochemistry

Liverworts are classified as bryophytes, and are distinguished from the other members of this order (mosses and hornworts) by having either flat-lobed leaf-stem structures or small leaves in rows of three. They can be found on tree trunks or growing on exposed soil, often in association with mosses. As such, they can become a troublesome weed in some horticultural situations (e.g., Lunularia cruciata).

Lunularia cruciata

Liverworts are ungrazed by animals, fungi and bacteria. This suggests that they contain antifeedant phytochemicals as morphologically they appear quite lush and succulent. Further evidence for their phytochemical activity can be seen in the history of the use of liverworts (along with other byrophytes) to cure cuts, burns and external wounds and as treatment for bacteriosis, pulmonary tuberculosis, neurasthenia, fractures, convulsions, scalds, uropathy, pneumonia and neurasthenia. While some of this may be attributed to the doctrine of signatures, they erroneous idea that plants shaped like body parts copuld be used to treat said body part research has shown that 700 terpenoids and 220 aromatic compounds have been isolated from liverworts, many of which show interesting biological activity. Liverworts are a greater source than the other Bryophytes of biochemicals as they contain cellular oil bodies, which are composed of lipophilic terpenoids and aromatic compounds (Asakawa(2001), Phytochemistry 56 pp. 297-312).

An example of one such phytochemical is Marchantin A. This bis(bibenzyl) is commonly found in Marchantiales species such as Marchantia polymorpha and shows antifungal, antimicrobial and muscle relaxing and cytotoxic activities.

Marchantia polymorpha

Due to the lack of a fossil record for bryophytes, the evolution of liverworts is unclear. However, two theories exit. The first is the progressive theory that suggests that bryophytes arose from algae and in turn gave rise to the pterioophytes (ferns and their allies such as horsetails and quillworts). The second (the reductive theory) suggests that green algae dave rise to primitive ancestor of vascular plants from which both the bryophytes and pteridophytes arose. Currently, researches at the Tokushima Bunri University in Tokushima, Japan are attempting to solve this riddle by examining the phytochemical links between the two orders.

Notes from Argeles - The Chirping of Crickets

Mediterranean field cricket (Gryllus bimaculatus)

A guest post by Ken.

The call of the cricket is produced by the male of the species by rubbing a stiffened vein “plectrum” of one wing over a toothed vein “file” of the other wing. This creates sound waves because of vibrations of the harp area in each wing. A sound pulse is produced by each closure of the wings. A chirp results from three to five pulses made in rapid succession. Interestingly, in the field cricket the chirp is temperature dependent affecting not only the chirp duration but also the period and frequency. (Communicatory Constraints on Field Crickets Gryllus bimaculatus Calling at Low Ambient Temperatures J. W. Van Wyk, J. W. H. Ferguson J. Insect Physiol. Vol. 41, No. IO, pp. 837-841, 1995)

I observed the Mediterranean field cricket (Gryllus bimaculatus) while on vacation in Argeles, France in 2009. He appeared to be very fond of my beach towel, either for the moisture or the shelter.

Au revoir, Monsieur le Cricket!

Door Snails Under Threat

The family Clausiliidae (door snails) are characterized by a sinistral shell that is often ribbed and fusiform or spindle shaped with a tapering spire forming a large number of whorls (Molluscs, Vaclav Pfleger, 1999 pp.102). They feed mainly on algae and lichens and often can bee seen emerging from crevices in dark damp areas such as rock faces and heavily mossed tree trunks.

The Craven Door Snail, Clausilia dubia

However, door snails and the non-marine molluscs of Ireland as a whole are under threat. Of the 150 species present, two are considered to be regionally extinct, five critically endangered, fourteen endangered, twenty-six vulnerable, six near threatened, and the rest of least concern, or data deficient (Red List of Non-Marine Molluscs 2009, Byrne et al.). Ireland’s non-marine molluscan fauna is of international importance. Ten species have populations of significant international worth, having large proportions of their global population in Ireland.

Of the Clausiliidae present in Ireland, two species are vulnerable (Balea perversa and Cochlodina laminata) while another two of least concern (Balea heydeni and Clausilia bidentata). Loss of these species could have an unknown knock on effect on the ecology of the island of Ireland.

Clausilia dubia

Do you like lichens?

A guest post by Ken.

And so to Currabinny woods, in search of lichens. Remembering my old lichen groups from college (and looking them up on the Internet as a reminder) Crustose, Foliose and Fruticose, I thought the identification would be a doddle. Not quite so.
Lichens are fungi that form stable self-supporting associations with either green algae or cyanobacteria. In lichens the fungus (mycobiont) is distinct from its free-living relatives both morphologically and in the production of unusual chemicals and is incapable of independent existence. The thallus, mostly consisting of the fungal hyphae, envelop the individual cells of the algae (photobiont) and it is the configuration of this thallus, crust-like (crustose), leaf-like (foliose), scaly (squamulose) or bushy (fruticose) that gives the first level distinction. Lichens can lie dormant in a dessicated state allowing them to survive the harshest habitats on Earth but they are extremely sensitive to air pollution. (The Diversity of Living Organisms R S K Barnes, 1998 Blackwell Science p124)

The first 6ft of different tree species was surveyed for different species of lichens.

The following observations were made:

The beech tree (Fagus sylvatica). On this tree we found a crustose lichen called Lecidella elaeochroma f. soralifera. Also present was Pertusaria hymenea (Pore lichen) and Phaeographis dendritica.

Beech tree (Fagus sylvatica)

Phaeographis dendritica

Lecidella elaeochroma f. soralifera with his friend, the beetle (Order Coleoptera)

Pertusaria hymenea

On a birch tree (Betula pendula) we found Lepraria incana (Dust lichen).

Silver birch (Betula pendula)

Lepraria incana on silver birch

On a fallen beech tree was the foliose lichen Parmotrema perlatum (Ruffle lichen), a woodrush (Luzula sylvatica) and the moss Polytrichum commune (see previous blog-entry on this moss).

Parmotrema perlatum on a fallen beech

Woodrush (Luzula sylvatica) and common haircap moss (Polytrichum commune)

On another fallen tree, this time a Japanese larch (Larix kaemferi), were Parmotrema perlatum again and two fruticose lichens Usnea subfloridana (Beard lichen) and Ramalina farinacea (Farinose cartilage lichen). These types of lichens were higher up in the tree but as it had fallen we were given the opportunity of photographing them up close.

Japanese larch with pink female flower

Usnea subfloridana

Ramalina farinacea

On an oak tree (Quercus sp.) we had more Pertusaria hymenea and some Lepraria incana.

Oak (Quercus sp.)

Pertusaria hymenea on oak tree

On Scots pine (Pinus sylvestris) we had more Lepraria incana.

Scots pine (Pinus sylvestris)

Lepraria incana

Overall the most common lichen, present on three of the tree species was Lepraria incana. This lichen species is found on shaded trees and this would be the case for a lot of the Currabinny trees. Or maybe we just like the quiet places.
We also saw a few varieties of fungus, one of which is an old friend of mine, Trametes versicolor. Another favorite was the plant Montbretia or St. Anthony's lily (Crocosmia x crocosmiiflora) which we had to confirm by unearthing its bulb (the woodrush had no such bulb) as none of its orange flowers were yet visible. We shall have to wait until July.

A fungus

Trametes versicolor (removed and placed on trunk)

Trametes versicolor a white-rot fungus

Montbretia (note the bulb)

Anyway until next time,
Ken.

Fern Species of Corkonian Limestone Walls

One of the most aesthetically pleasing aspects of Cork city and its environs are its numerous limestone walls. Many buildings of note up to the early 20th century were constructed or façaded with locally quarried limestone and may have limestone walls surrounding them. Even the river Lee as it passes through the city is bordered, for the most part, by limestone quay walls. These walls are also mortared with limstone. All of this mimics perfect habitats for plants that thrive on a calcareous substrate. Due to little if any organic matter, most flowering plants decline these walls in favour of the dirt-rich cracks where they meet the footpath. Often not even this is an option as the built up nature of the environment limits the light available. These conditions do lend themselves to an often perfect environment for certain fern species.

Limestone wall with Polypodium vulgare and Asplenium ceterach

The most frequent to be seen is the Common Polypody (Polypodium vulgare). This tends towards the upper third of walls, especially the top which it may often cover uninterrupted for some distance. Their bright green colour is complemented by vibrant yellow sori which ripen from July onwards. Common Polypody, along with the other species mentioned here,

Polypodium vulgare

Walls in the city centre contain three other fern species. Hart’s Tongue Fern (Asplenium scolopendrium) is often seen, but with a much reduced frond size from samples growing in areas of higher organic matter content, such as hedgebanks and ditches. Whereas fronds in these conditions can grow as much as 60 cm, on limestone walls they tend to between 10 – 20 cm. This reduction in size does not affect dispersal however, and once established populations will persist.

Asplenium scolopendrium

The species that tends to have the largest individual size is the Maidenhair Fern (Asplenium trichomanes). The prostrate growth habit of the fronds combined with their large relative length (up to 35cm on limestone walls) and tough, black stalks means this can often be the most evident fern on a wall.

Asplenium trichomanes

Probably the least conspicuous fern is the delicate Wall Rue (Asplenium ruta-muraria). The young fronds are easily confused with Cardamine spp., however the mature plant has a delicate beauty all of its own.

Asplenium ruta-muraria

Outside the city centre, all of the above species persist, along with one other. Rustyback (Asplenium ceterach) is so named because of the rust covered scales that cover the underside of the fronds. Its absence from the centre of the city is unclear as it's response to pollution and light intensity (both of which vary detrimentally closer center) is similar to the species mentioned above.

Asplenium ceterach

These fern species lend a beauty and character to the otherwise plain limestone walls on which they grow. Unfortunately many are being removed or treated with herbicide to clean up the walls. Unlike larger, woody plants (such as Buddleja spp.), their rooting and growing does not affect the integrity of the walls and so should be left to decorate the city.

The threat of the Australian Flatworm

Ireland has been subject to invasion by a number of alien species down through the years. Some, such as the beech tree, date from prehistoric times. However other, more recent invaders are having a detrimental effect on the country's native species. Montbretia (Crocosmia x crocosmiiflora) is displacing species like Irish Spurge (Euphorbia hyberna) in hedgebanks. Zebra mussels (Dreissena polymorpha) not only clog waterways, but also decimate microalgae populations. Rhododendron ponticum threatens the biodiversity of native oak woodlands of Glenveagh, Glengarriff and Killarney by a combination of shading over young trees and shrubs and exudation of toxins into the soil. Indeed, according to Invasive Species Ireland, there are 250 hectares infested with R. ponticum in Killarney National Park alone.

Another unwelcome intruder is the Australian Flatworm, Australoplana sanguinea alba. This was first reported in Belfast and Dublin in 1983 and in the interim has spread to the entire island. A. s. alba feeds on earthworms, however not to the same extent as the ravenous New Zealand Flatworm, Arthurdendyus triangulatus. Its impact on native species has not yet been fully understood. Research carried out at the University of Manchester by Giulio Santoro and Hugh Jones suggests that A. s. alba, while not having a significant effect on overall earthworm population, selectively fed on anaeic earthworms. These are species that burrow deep in the soil and their decrease in an area leads to a reduction in soil drainage. This is especially serious in heavy soils that are prone to water-logging. Since much of the grazing land in Ireland is of this type, the Australian Flatworm may pose serious problems not only to the island's biodiversity, but also to its agriculture in the future.

To walk among mosses

Spring is somewhat of a stranger this year. The record cold of the winter has dragged on to a point where now, in mid March, the swathes of yellow daffodils so common in other years are much delayed. Snowdrops are making a gallant effort in the open, but only the brave crocus has unsheathed its full regalia, leaving fairy sized cups of yellow, white and purple to break through the grass. Elsewhere the catkins of the alder and willow and the remaining copper leaves of the beech strive to bring colour to the cold, short days. 

However it is the green of mosses that are most conspicuous at this time of year. They lie verdant among the blackened remains of other plants ravaged by harsh frosts. It is their ability to survive these frosts that allows them to carpet areas at this time of year. Frost causes irreversible frost damage to plant cells due to mechanical forces generated by growth of extracellular ice crystals as well as cellular dehydration and increased concentration of intracellular salts (Manabu Nagao, 2004). Mosses have the cell structures and mechanisms to overcome these stresses.

On closer inspection, the range of mosses present in relatively small area is equally impressive as their resilience. The delicate fronds of the Tamarisk (Thuidium tamariscinum) vie with the common haircap (Polytrichum commune) for attention, while the shining Hookeria (Hookeria lucens) shimmers ghost-like between the two. Take time to inspect them before their showier relatives turn up!

Hookeria lucens

Thuidium tamariscinum

Polytrichum commune

Mnium spp.

Brachythecium spp.

Mnium spp.