Giant Rhubarb

Gunnera are big. Very big. Well, not all of them: Gunnera herteri stands only 6 cm tall (1). But the big ones are very big. They're old too, with the fossil record showing they have been in existence for at least 95 million years. It is their size, however, that is most obviously impressive. G. mantica has a leaf diameter of 3 m (1). Its not alone in this, with many other of the c. 50 species of this monogeneric family towering, in some cases 6 meters, over any other vegetation.

Gunnera tinctoria

This height has posed a problem in Ireland where the species G. tinctoria was was introduced from its native Chile some time in the past 100 years, probably as a ornamental. While not as big as enormous as some of the Gunnera giants, it still clocks in at an impressive 2 meters tall with leaves 2 meters in diameter. It tends to grow in dense colonies that out-compete and displace native vegetation. It was first recorded wild here by the renowned Irish botanist Robert Lloyd Praeger in 1939 on Achill Island, Co. Mayo and it is here today that the plant colloquially called 'Giant Rhubarb' shows the extent of its dominance (2). Large tracts of the island are now almost entirely covered with G. tinctoria. As such, it is considered an invasive in the west of Ireland where it has colonised many habitats such as grassland, waterways, roadside verges, bogs, heaths and coastal cliffs (3). While its sparse distribution throughout the rest of the country may be reflective of the different climatic conditions there, it may also may just be evidence of the beginning of its invasion. 

Gunnera tinctoria leaf

While the size of G. tinctoria accounts for its adverse effect on other plants, it is its methods of reproduction that account for its invasive nature. As a perennial rhizomatous plant, it can spread easily from year to year once established. It also produced many seeds which may be carried to new sites by birds feeding on them (3). Ireland's wet climate also assists these damp loving plants, which accounts for their status as an invasive in similarly inclement New Zealand. The rhizomes mean mechanical removal may not always be effective, so herbicides such as Round-Up are a valuable tool in controlling the plant. 

Gunnera tinctoria flowering parts

Other than their height, Gunner species also possess a distinct adaptation that singles them out from all other flowering plants. They form symbiotic relationships with Nostoc cyanobacteria (4). The cyanobacteria are uniquely harboured internally by the plants which surround the Nostoc filaments with membranes where they fix nitrogen for the plant. Entry is made via specialised glands on the Gunnera stems. Interestingly it has been shown that G. manicata grown on substrate with sufficient nitrogen did not develop these glands (4).

References:

1. Wilkinson, 2000. Botanical Journal of the Linnean Society 134 pp. 233-266
2. Praeger, 1939. Proceedings of the Royal Irish Academy 45B pp. 231-254
3. Armstrong et al., 2009. Giant Rhubarb (Gunnera tinctoria) Invasive Species Action Plan
4. Chiu et al., 2005. Plant Physiology 139 pp. 224-230

A Soldier Fly, Sargus bipunctatus

Two Spotted Centurion, Sargus bipunctatus

Soldier flies, family Stratiomyidae, are so name because of the bright, almost militaristic colours of their body parts. Over 2800 species are described worldwide, varying widely in appearance, ranging in size from 3 to 30mm, possessing spines on the scutellum numbering from zero to eight, and bearing colors of metallic green, red, yellow, and black (1). Thirty two species are recorded in Ireland (2). Of these, one of the largest and certainly most attractive is the Two Spotted Centurion (Sargus bipunctatus). Ranging in size from 11 to 14 mm, there is pronounced sexual dimorphism between sexes. Males are are bright green, while the femals have an intense brown-red abdomen (3). Males and females have two white spots on their heads. Both adult forms can be seen on the wing from early July to late October (4), but rarely after mid October: larvae are to be found in dung compost and other rotting material, where they feed on detritus (5).

Two Spotted Centurion, Sargus bipunctatus

 References:

1. Brammer and Dohlen, 2007. Molecular Phylogenetics and Evolution 43 pp. 660-673
2. Ferriss et al., 2009. Irish Biodiversity: a taxonomic inventory of fauna p. 101
3. Reichholf, 2007. Entomofauna 28 pp. 141-148
4. Drake, 1991. Provisional atlas of the Larger Brachycera (Diptera) of Britain and Ireland p. 21
5. Roberts, 1969. Journal of Zoology 159 pp. 381-398

The Royal Fern

Fertile Frond of the Royal Fern, Osmunda regalis

Some ferns are quite similar. The small filmy ferns Wilson's Filmy Fern (Hymedophyllum wilsonii) and Tunbridge Filmy Fern (H. tunbrigense) are virtually identical at first glance, with subtle features like the presence or absence of toothed edges on the scales protecting the sori having to be examined to differentiate them. One fern that doesn't have that problem though is the Royal Fern, Osmunda regalis. A strikingly distinctive fern, found in wet bogs and fens throughout Ireland (with a global distribution spanning Europe, Asia and Africa) its fronds can reach heights of 160 cm (1). Most of these are sterile, with the fertile fronds rising above the others in the centre of the plant. Their shuttlecock-like appearance and the fern's overall imposing height are unmistakable.

The Royal Fern, Osmunda regalis

Or are they? Homosporous ferns have two free-living generations, the sporophyte generation which is what most people would call the fern, and the relatively short lived gametophyte generation. The gametophyte generation is much smaller and shows far less morphological complexity. This means that identification is often next to impossible. Identification of fern gametophytes is important as they play an important part in fern dispersal and ecology. This problem has been overcome by the use of DNA-based identification. A sample of a gametophye in cultivation that was unknown for 30 years was identified as O. regalis using plastid sequencing (2). The gameteophyte never produced antheridia, and so never produced the sporophyte stage, and morphological analysis was inconclusive. Its identification as O. regalis shows the power of DNA-based techniques in revealing more about the ecology of fern gametophytes.

References:

1. Phillips, 1980. Grasses, Ferns, Mosses and Lichens of Great Britain and Ireland p. 105
2. Schneider and Schuettpelz, 2006. Molecular Ecology Notes 6 pp. 989-991

The Pill Millipede Misleads with Convergent Evolution

The Pill Millipede (Glomeris marginata)

One of the most striking examples of convergent evolution I have come across is that of the Pill Millipede (Glomeris marginata) and the Pill Woodlouse (Armadillidum vulagre). Convergent evolution describes the acquisition of the same biological trait in unrelated lineages (1), and in both these animals the architecture of their exoskeleton allows them to curl into a ball (or “pill”) when alarmed. Closer examination of both species shows they are obviously not related, the most distinguishing feature being that G. marginata has two pairs of legs per segment, and many more to boot than the seven pairs possessed by A. vulgare. G. marginata also has shorter antennae and its dorsal plates are edged with cream rims. It can be found in leaf litter in mature woodlands (2), whereas A. vulgare is far more common - individuals can often be happened upon in urban gardens.

Convergent Evolution: Pill Millipede (Glomeris marginata) on left and Pill Woodlouse (Armadillidum vulgare) on right.

However, G. marginata may have further features, that show its apparent relatedness to insects, that are a result of convergence. Traditionally, morphological features such as loss of second antennae, formation of Malpighian tubules, postantennal organs and trachea have indicated that the myriapods are close relative to the insects (3). Yet these features have been shown to be prone to convergence (4), and molecular evidence also points to a far more distant relationship than previously thought. Of the four extant arthropod subphyla, the hexapoda and crustaceans are now seen as sister groups and mitochondrial genome analysis has revealed the same to be true for the myriapods and the chelicerates (5). This is backed up further by 18S/28S rRNA sequences and Hox gene analysis of the myriapods (3)

Overturned Pill Millipede (Glomeris marginata)

Analysis of neurogenesis in G. marginata has provided morphological evidence to support these claims (3). In the development of neuroblasts in G. marginata, groups of cells invaginate to form the the ventral neuroectoderm. This is similar to neurogenesis in spiders, but quite different than that in insects where single cells give rise to the neuroectoderm.

References:

1. Miller et al., 2010. Convergent Evolution
2. Sterry, p. 172
3. Dove and Stollewerk, 2003. Development 130 pp. 2161-2171
4. Dohle, 2001. Annales de la Societe Entomologique de France 37 pp. 85-103
5. Hwang et al., 2001. Nature 413 pp. 154-157

Skeletoniser!

The Blackberry Skeletoniser, Schreckensteinia festaliella

Schreckensteinia festaliella is the only member of the bristle leg moths, family Schreckensteiniidae, to occur in Europe, and only one of five species in whole the family. Although it is a small (c. 10 mm) moth, it has a fearsome common name: the Blackberry Skeletoniser. Putting one in mind of a character from the 1980's cartoon serial 'He-Man', it gets this name from the larvae's feeding habits on blackberry and other Roseacea species (1). Attacks can lead to extreme damage, leaving nothing but skeletons of leaves on plants, hence the name. However, only one case of severe damage to cultivated crops has been noted, that of Raspberries in Scotland (2).

The Blackberry Skeletoniser, Schreckensteinia festaliella, in distinctive repose with hind leg raised. Note the spines on the hind leg.

The bristle leg moths get their name from the quite large spines that occur on the hindmost legs. The slender winged adults are may be seen in repose with, quite distinctively with their hind legs raised and projected over the abdomen. Although native to Europe, S. festaliella was introduced to North America between 1963 and 1969 to control invasive wild blackberry (Rubus argutus) (3).

References:

1. Capinera, 2008. Encyclopedia of Entomology p. 564
2. Alford, 2007. Pests of Fruit Crops: a Colour Handbook p. 238
3. Nagata and Markin, 1986. Proceedings of the Sixth Conference of Natural Science, Hawaii Volcanoes National Park pp. 541-547

Tree Lungwort and the Doctrine of the Signatures

Tree Lungwort, Lobaria pulmonaria

Spleenwort, Liverwort, Toothwort: seemingly picaresque names for common plants, their origin is actually based in an ancient concept of medicine, the Doctrine of Signatures. The early botanist – and all-round occultist – Paracelsus von Hohenheim (1493-1541) was the first to expand on ideas from antiquity and early European Christianity as the Doctrine of Signatures (1). The central tenet of the doctrine was that the shape, colour and other attributes of a plant indicated its use in healing. So the liver-shaped thallii of the Liverwort genus Marchantia spp. are, according to the doctrine, useful for treating liver ailments*. The Doctrine of Signatures was based on the belief that God marked all his creations with a sign, or signature. The sign showed its purpose. Its rise in popularity during the 15th and 16th centuries is rooted in the role 'resemblance' played in Western culture at that time.

Tree Lungwort, Lobaria pulmonaria

While the Doctrine of Signatures has long been rejected by botanists and chemists on the basis of scientifically controlled data, it has left us with a plethora of colourful names. However, one of these is, in a way, well deserved. Tree Lungwort (Lobaria pulmonaria) is an impressively large lichen that has the green alga Dictyochloropsis reticulata as its photosynthetic partner (2). It is found attached to the bark of trees in old to ancient woodlands with high levels of rainfall (3). While the pitted appearance of the thallii resemble lung tissue, the name 'Lungwort' is appropriate in another sense. Found in moderate regions of the tropics and throughout boreal regions of the norther hemisphere, it thrives in places of low pollution and has dissappeared entirely in parts of Central Europe in the 20th century due to falling air quality (4). Pollutants in the atmosphere condensing to form acid rain fall on the forests. L. pulmonaria colonise drainage channels below old and large wounds on deciduous trees. These channels are richer in minerals and had a higher pH than normal bark (5), but concentrate pollutants in rain. Populations of the lichen are thus wiped out

Tree Lungwort, Lobaria pulmonaria showing fruiting bodies

While the effect of L. pulmonaria on the lungs has yet to be proven, it has been shown to have some  pharmacological properties (6). Liquid extracts from the lichen tested on rats showed moderate anti-inflamatory and strong antiulcerogenic affects.

*Note: The suffix 'wort' is derived from the old English word for plant.

References:

1. Pearce, 2008. European Neurology 60 pp. 51-52
2. Widmer et al., 2010. Fungal Biology 114 pp. 583-544
3. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 282
4. Walser et al., 2003. Fungal Genetics and Biology 40 pp. 72–82
5. Gauslaa, 1995. The Lichenologist 27 pp. 59-76
6. Süleyman et al., 2003. Phytomedicine 10 pp. 552-557

Notes on Irish Orthoptera with a Provisional Checklist

The Orthoptera are the grasshoppers, groundhoppers and crickets. Twelve species are found in Ireland and regarded as native (1). Throughout the 19th and 20th centuries, a lack of attention was paid to Irish Orthoptera, with a few exceptions (2). Therefore the true extent of distribution of species may not reflected in the literature.

Irish Orthoptera Species

Family	Species	Common Name	Note
Tettigoniidae (Crickets)	Conocephalus dorsalis	Short Winged Cone Head	First recorded in 1989
	Leptophyes punctatissima	Speckled Bush Cricket	Found in south
	Meconema thallsainium	Oak-Bush Cricket	Found in south-west
	Metrioptera roeselii	Roesel's Bush Cricket	First recorded in 1977
	Pholidoptera griseoaptera	Dark Bush Cricket	First recorded in 1983
Tetrigidae (Groundhoppers)	Tetrix undulata	Common Ground Hopper	Widespread
	Tetrix subulata	Slender Ground Hopper	Restricted to Galway
Acrididae (Grasshoppers)	Myrmeleotettix maculatus	Mottled Grasshopper	Widespread but local
	Chorthippus brunneus	Common Field Grasshopper	Widespread
	Chorthippus albomarginatus	Lesser Marsh Grasshopper	First recorded in 1960
	Omocestus viridulus	Common Green Grasshopper	Widespread
	Stethophyma grossum	Large Marsh Grasshopper	Found in west

Five species of grasshopper are present in Ireland (see table). Chorthippus brunneus and Omocestus viridulus are the most common, both being found in a variety of grassy places (3). Myrmeleotettix maculatus prefers drier areas such as dunes and heaths and therefore tends to be more local. Ireland's largest grasshopper, Stethophyma grossum, is locally restricted to floating acid bogs in the West of Ireland. C. albomarginatus is the most recent addition to the Irish grasshoppers, with a first record in 1960 (2). It is restricted to a few site in the south-west, favouring grassland and dunes.

Common Green Grasshopper, Omocestus viridulus

The grounhoppers are a family of orthopterans that resemble grasshoppers, but are much smaller in size. Unlike other Orthoptera, most groundhoppers overwinter as adults. Two species are present in Ireland. Tetrix undulata is of widespread but local occurence. T. subulata is similar in appearance, but has a longer protonum and wings and is restricted to Galway.
Crickets in Ireland are less common than grass- or groundhoppers. Five species of crickets are present in Ireland, with three of these being first recorded only in the last 34 years. Leptophyes punctatissima can be found in hedgerows but is restricted to the local areas in the south of Ireland and quite scarce. Meconema thallsainium is again restrcited to the south west of the country, favouring woodlands, but may also be seen sometimes in gardens. Found in damp meadows, Metrioptera roeselii was first recorded in 1977 (2). Pholidoptera griseoaptera was first recorded in Ireland in 1983 in the south east (4). it is found in in hedgerows and amongst scrub near sea cliffs and dunes. The most recent addition to the list of Irish orthopera is Conocephalus dorsalis. This was recorded in 1989 in the south west prefers two distintct habitats: coastally on saltmarshes and sand dunes and inland on lowland bogs and fens.

Common Field Grasshopper, Chorthippus brunneus

As well as frequent records of one-off species arriving on imported produce, three other orthoptera species of note have been recorded in Ireland. The European Mole Cricket, Gryllotalpa gryllotalpa, was recorded in from one site in Northern Ireland pre 1970, but is not considered native. The non-native House Cricket Acheta domesticus was present in Ireland until about 1960, but although recent sightings have been reported (5), it is now considered rare or absent. The Greenhouse Camel Cricket, Tachycines asynamorus can be found as an introduced species in Ireland, but as it tends to become established in artificial situations such as greenhouses, it is not included in the Irish list of Orthoptera.

References:

1. Ferriss et al., 2009. Irish Biodiversity: A Taxonomic Inventory of Fauna p. 108
2. Haes and Harding, 1997. Atlas of grasshoppers, crickets and allied insects in Britain and Ireland
3. Sterry, 2004. Collins Complete Guide to Irish Wildlife p. 124
4. O'Connor and O'Connor, 1985. Entomologists' Gazette 36 pp. 229-232
5. O'Connor, 1993. Irish Naturalists' Journal 24 p. 337