Rare ferns

Several species of ferns have been recorded from the Maltese islands. Most are rare or very rare. On the other hand one species, the maiden hair fern, known in Maltese as tursin il-bir, is relatively common. It can be found in caves, wells, in valley bottoms and in damp courtyards of old buildings. 

Like many other ferns it thrives in humid habitat away from direct sunshine although some species such as the rusty-back fern (felċi tal ħitan tas-sejjieħ) can live in full sun and requires little humidity. This species is found in Western and Central Europe including the Mediterranean. In Malta it is very rare. The only time I saw it, it was growing on a large boulder in the middle of a dry valley in a spot not reached by the rays of the sun. In some parts of Europe it was used medicinally as a diuretic.

Most other ferns recorded in the Maltese island are also very rare with some species not having been seen for decades. Two or three species are aliens, that is, they were imported into Malta, probably as cultivated species, and can now be found growing wild.

Ferns are primitive plants. They have stems, leaves and roots like other vascular plants but instead of seeds they produce spores and thus do not have flowers. About 12,000 species are found in the world. About twelve have been recorded in the Maltese islands.

The oldest fern fossil records are from 360 million years ago. In geological terms this would be the beginning of the Carboniferous period which lasted until 299 million years ago. The name of this period comes from ‘carbo’ which is the Latin word for coal as during this period many of the coal beds were laid. 

The coal formed because of the appearance on earth of bark bearing trees which found the right climatic conditions for growth and possibly also because the animals and decomposing bacteria which can digest lignin, the main component of wood had not yet evolved with the result that the wood remained on the ground until it was covered by sediment and eventually changed into coal 

This article was published in The Times on 27/07/2011

Watching Cory’s shearwaters

Cory's shearwater (Calonectris diomedea)

This weekend I took part for the second year running in a Birdlife Malta boat trip to watch Cory’s shearwaters off Gozo. Seeing the enthusiasm of the participants while watching the shearwaters brought to my mind pictures I have seen of tourists watching whales in other parts of the world.

Whale watching is attracting millions of people worldwide. The first whale watching trips took place in 1955.

During that year 10,000 persons paid US $ 1 per trip to be able to get close to the whales. 

By 2008 the number of persons watching whales had risen to 13 million. It is estimated that these generated US $ 2.1 billion in tourism revenue annually.

Watching shearwaters in Malta offers an unforgettable experience that is probably as exciting as whale watching. The Cory’s shearwater, known in Maltese as Ċiefa, is a large bird that looks like a long-winged gull. It flies just above the water surface keeping its wings open to make the most out of air currents that form just above the water surface. It is well adapted for life at sea and approaches land only to breed. 

The Cory’s shearwater nests in colonies, usually under boulders or in crevices in undisturbed cliffs. During the day the colonies are very quite and one does not realize that hundreds of birds could be present close by. During the night the colony becomes alive with the loud calls of the shearwaters as these birds visit the nests to relieve their partner and after the eggs hatch to feed the young birds.

At least 5,000 pairs of Cory’s shearwater breed in the Maltese islands. The largest colony is found at Ta’ Cenc in Gozo.

Shearwater watching can become more popular in the Maltese islands and can even attract a good number of specialized visitors to the Maltese islands. Furthermore such activities can help to create more awareness about the Maltese natural environment. 

This article was published in The Times on 13/7.2011

The chicories' medicinal properties

Chicory (Cichorium intybus)

The chicories are perennial plants that add a touch of colour during the summer months. The most common is the chicory, ċikwejra in Maltese. Its light blue flowers can be seen between May and October. Anybody visiting the countryside during the warmer months is likely to see the plant protruding out of the dry vegetation. It grows throughout most of Europe although it is doubtful whether it is native in northern parts.

The spiny chicory is less common but can also be found with a little effort. In Maltese it is known as qanfuda meaning like a hedgehog an obvious reference to its shape and spines. The flowers which appear in May are very similar to the more common species but the flowering season is much shorter and they disappear by the end of July. This species is native to the Mediterranean region and is well adapted for the region’s hot dry summer.

The chicory has been cultivated in Europe for many centuries as a medicinal plant. In some countries, especially in poorer regions, the roots are baked and ground to be used as a substitute for coffee.

Chicory contains chemicals that can eliminate internal parasites such as worms and it is sometimes added to animal forage to help reduce internal worms. It is also said to have many other medicinal properties including as a treatment for gallstones, gastro-enteritis, sinusitis, and for cuts and bruises.

A related species, the endive, is also found in Europe. Several varieties of this species are cultivated in many countries including Malta although it does not seem to be as popular as other leafy vegetables such as lettuce and spinach even though it is known to be very healthy as it is rich in vitamins A and K, minerals, foliate and it is also high in fiber. It is available for sale in spring at about the same time as the globe artichoke and the two are often cooked together as their tastes compliment each other. 

This article was published in The Times on 18.05.2011

The harmful effects of herbicides

A few weeks ago I wrote that road side verges provide the right conditions for many species of flora and fauna. I also wrote that I had not seen herbicides being used to re­move this vegetation for many years and I was hoping that this practice had stopped. Last week I saw two teams in different parts of Malta using herbicides on pavements.

I do not understand this obsession to remove any living things from built up areas. Wild plants not only provide habitat and food for butterflies, bees and other insects but also have aesthetic value. They add colour to their drab surroundings and cover ugly concrete and rubbish. But, while accepting that some people cannot appreciate nature and use their power to anihilate it, it is unacceptable that herbicides are sprayed on pavements.

Herbicides are poisons that are used to kill vegetation. Many if not all of them can also harm humans, pets and wildlife. The toxicity of herbicides varies greatly as does the time taken for them to break down. Some are programmed to decompose after a relatively short time so that crops can be sown in soil after they have been sprayed but, while the breakdown products might not kill plants, there is no guarantee that these products do not harm humans and other animals.

Furthermore, anybody using a pavement has no option but to walk on poisoned ground. Children and pets are more vulnerable to poisons and their small size and the fact that they are closer to the ground makes absorption of poisons faster and easier. And even if children and pets had to be kept inside, a person walking on a poisoned pavement can unwittingly collect poison on his or her shoes and transfer it to his or her home where his children or pets come in contact with it.

There are indications that some herbicides are carcinogenic and, although acute toxicity comes only from exposure to large quantities of herbicides, even low doses might have long-term problems.

Using herbicides to remove vegetation might be the cheapest way to remove unwanted vegetation but our health and environment are worth more than that.

This article was published in The Times on 11.05.2011

The island bluetail damselfly

Island bluetail damselfly (Ischnura genei)

The island bluetail damselfly is a delicate insect known in Maltese as damigella. It is closely related to the more robust dragonflies. 

It lives in valleys with running water and near ponds, pools and reservoirs. 

It is a weak flyer and does not stray too far from aquatic habitats on which it depends throughout its life cycle. Like dragonflies the damselfly lays its eggs in water. The larva spends its entire life under water feeding on smaller organisms.

Two forms of this species are found in two colour forms: green and reddish-brown. Both forms can occur in a particular place and the colour might a result of different environmental temperature during the larval stage of the damselfly. 

In other insect species larvae that are developing later in the season, when the temperature is higher give rise to brown adults which are thus better camouflaged in the dry summer vegetation. As far as I know this has not been investigated in damselflies but a future study might show such a link.

Like dragonflies, it has very interesting courtship and mating habits, quite different from that of other insects.

The genital opening is near the tip of the tail, but before mating the male transfers his sperm to an accessory genital organ on the underside of his abdomen, just behind the thorax. 

He then finds a female and seizes her by the neck with a pair of claspers situated at the hind end of his body. They then fly in tandem and settle, linked together in this way.

When mating takes place, the female bends her body around under the male’s body and the sperm is transferred for fertilization.

Damselflies and dragonflies use different methods to lay eggs. Some insert them in the plants of aquatic plants or in vegetation at the water’s edge. 

Others fly over the water and drop them, while others dip the abdomen into the water to wash the eggs off the tip. Some species remain in tandem whilst the female is laying.

Their larvae or nymphs spend all their time under water hunting smaller animals. A hunting larva stalks its prey to within a centimetre or less, than shoots out the labium and seizes its prey with its claws. 

The victims are mostly insects, but large well-grown larvae can even catch tadpoles and small fish. The labium is a segmented organ, found in all insects below the mouth. In dragonfly larvae this organ bears a pair of pincer-like jaws near the tip and is elongated and hinged so that it can be extended in front of the head.

This article was published in The Times on 20.04.2011

The Scilly buttercup

Scilly buttercup (Ranunculus muricatus)

The Scilly buttercup is a species of buttercup which is sometimes also known as the spiny-fruit buttercup. It is native to Europe, but it can be found in many other places in the world, including parts of Africa, Australia, and the western and eastern United States, as an introduced species and agricultural and roadside weed. It grows in wet habitats, such as irrigation ditches. 

In Malta it is found in humid valley bottoms such as at Chadwick Lakes and Fiddien. It is an annual or sometimes biennial herb producing a mostly hairless stem up to half a meter long which may grow erect or decumbent along the ground.

The buttercups belong to a large genus of plants that can be found almost throughout the world. It consists of about 400 species some of which are terrestrial while others are aquatic. In the genus, known as Ranunculus, we also find the spearworts, water crowfoots and the lesser celendine. 

The name Ranunculus derives from the Latin words rana (frog) and ulus (little). This probably refers to many species being found near water, like frogs. Most buttercup species are poisonous when eaten by sheep, and other livestock but they are left alone because they have a bitter taste and have a blistering effect on the mouth caused by the poison.

Most of the species have bright yellow or white flowers. If the flowers are white they have a yellow center. In many species the petals are highly lustrous making it difficult to photograph them especially in direct sunlight.

In Malta at least 13 species have been recorded some of which are aquatic and can be found floating in pools and streams especially in the numerous small pools found in the rocky habitat known as garigue.

All Ranunculus species are poisonous when eaten fresh by cattle, horses and other livestock but their acrid taste and the blistering of the mouth caused by their poison means they are usually left uneaten. Poisoning can occur where buttercups are abundant in overgrazed fields where little other edible plant growth is left, and the animals eat them out of desperation. Symptoms include bloody diarrhea, excessive salivation, colic, and severe blistering of the mucous membranes and gastrointestinal tract. 

When Ranunculus plants are handled, naturally occurring ranunculin is broken down to form protoanemonin, which is known to cause contact dermatitis in humans and care should therefore be exercised in excessive handling of the plants. The toxins are degraded by drying, so hay containing dried buttercups is safe.

This article was published in The Times on 13.04.2011

The pomatias

Pomatias sulcatus

I recently took some pictures of an interesting species of snail but although I found its scientific name I could not find a common name for it so as its scientific name is Pomatias sulcatus, I used part of this name for the title of this article.

This species of land snail is found throughout the western Mediterranean. It is common on calcareous soils near the coast and inland. It can be found on soil, in crevices in rocky ground, under stones and among fallen leaves. Sometimes it buries itself in the soil while the specimens I photographed were living on a tree trunk. In the Maltese island it is common on Malta, Gozo and Comino as well as on some of the smaller islands.
There was and probably still is some controversy about this snail in the Maltese islands. Some biologists have listed it as a distinct species endemic to the Maltese island others as a subspecies while others believe that the snails found on Malta are not different enough from the snails found in other parts of the Mediterranean to be considered as a separate species or subspecies.

Pomatias sulcatus is not the only species of pomatias that can be found in the Maltese islands. Another species, Pomatias elegans which is known as the round mouthed snail, can be found at San Anton Gardens at Attard. It probably found its way there on imported plants. This species is common in southern Europe and lives in similar habitats as Pomatias sulcatus.

The pomatias are one of the few groups of land snails that have an operculum. This is a calcareous structure like a small lid that fits neatly in the opening of the shell sealing the soft body inside. The operculum is found in most species of marine and freshwater snails but very rarely in land snails. Its main function is to prevent desiccation especially in those species that live in the intertidal or splash zone of the coast. The presence of an operculum in the pomatias suggests that these snails evolved from marine snails. 

This article was published in The Times on 06.04.10