The eucalyptus tree

Most of the 700 or so species of eucalyptus trees are native to Australia. A small number of them are native to New Guinea and Indonesia and one species is found in the Philippines. Several of these species have been planted in other parts of the world. At least three species have been planted in the Maltese countryside, often to the detriment of local flora.

The roots of many species of eucalyptus are able to draw up water very efficiently and can dominate the flora in arid zones. In many countries they were planted to drain marshes.

In the 1930s Mussolini planted thousands of eucalyptus trees in the marshes around Rome as part of an attempt to drain them and create new agricultural land and destroy the habitat of the anopheles mosquito which transmits malaria.  

In Malta eucalyptus trees are often planted by bird hunters because they are fast growing and within a few years they are large enough to lure migrating birds within range of the waiting hunters. In Maltese eucalyptus trees are known as ewkaliptu but many hunters use the name siġra tal-gamiem meaning the bird of the turtle doves.

The three species of eucalyptus that have been planted in the Maltese islands flower at the end of summer. The flowers of the commonest species, the red gum eucalyptus consist of an ovary surrounded by a large number of stamens topped by pollen-carrying anthers.

The flowers are rich in nectar and pollen and attract large numbers of bees. Many Maltese apiarists nowadays depend on the presence of these trees to harvest honey during autumn. For some apiarists eucalyptus trees have become so important that they protested when eucalyptus trees were cut down. They even appealed for more eucalyptus trees to be planted.    

Eucalyptus trees are still being planted by hunters in the Maltese countryside. This practice should stop and trees that have already been planted should be replaced by indigenous species such as Holm oak (siġra tal-ballut) and Aleppo pine (siġra taż-żnuber). Eucalyptus trees in built areas could be kept and perhaps more could be planted to provide bees with nectar when few if any other sources of nectar are available.

This article was published in the Times of Malta on 11 September 2013.

The tree house leek first grown as a house plant

Tree house leek (Aeonium arboreum)

There are many species on non-indigenous plants in the Maltese countryside. 

These are native to other countries but have established themselves and become naturalised in the Maltese islands. Many of them were brought to Malta as garden plants 

The Cape sorrel, (ħaxixa ngliża) was grown at the Argotti Gardens in Floriana at the beginning of the nineteenth century . It is a native of South Africa but found the conditions in the Maltese countryside to be so favourable that after a short while it established itself in the Maltese countryside and became very common everywhere.

Another alien species is the tree house-leek which is known in Maltese as kalluwa. 

This species was first grown in Malta as a garden plant. It was often planted close to farmhouses and eventually started to grow wild in the Maltese countryside.

 It is now considered as a naturalised alien species. It is a succulent, subtropical member of the genus Aeonium. 

This name is derived from the ancient Greek word aionos which means immortal. This genus consists of about thirty-five species most of which are native to the Canary Islands. A few species are found in Madeira, Morocco and in eastern Africa. 

The climate of the Canary Islands is fairly similar to that of the Mediterranean and many of the species manage to grow very well in Mediterranean countries including Malta.

Between the end of December and late February the tree house-leek produces a large number of bright yellow flowers that grow on an ovoid structure. The leaves are attached to the main stem and grow wrapped around it to form a rosette.

The tree house-leek is the most commonly cultivated aeonium.

 In winter it produces numerous bright yellow flowers on compact ovoid structures. Several varieties and hybrids exist including some with brown or variegated leaves. In gardens they can grow up to two metres but in Malta I have never seen a plant more than one metre high.

This article was published in the Times on 1.12.10

Alien plant species on the increase

Malta’s plant and animal life can be divided into indigenous (native) and alien (introduced) species. The introduction of plants and animals in the Maltese islands has been going on since prehistoric times. 

The excavations at Għar Dalam unearthed the fossilised remains of black rat, brown rat, cattle, sheep, pig and cat as well as domesticated plants such as wheat, barley and lentils. 

The introduction of alien species continued throughout historic times and the trend is that it is increasing as a result of an increase in commercial activities.

Most introduced species do not survive in nature and if they do they disappear after a short time but some manage to establish themselves and even become common sometimes to the detriment of indigenous species.

Alien species arrive in the Maltese islands for a variety of reasons. Some are introduced for agriculture and aquaculture. The sulla (silla) is grown for fodder but can also be found on clay slopes. Some such as the castor oil tree (siġra tar-riċċnu )have been introduced as ornamental plants while the cape sorrel (ħaxixa ngliża) which is now the commonest plant in Malta was originally grown in the Argotti Botanical Garden in Floriana. 

Several species of plants were imported with bird seeds and crop seeds these include the canary grass which has become naturalised.

Successful aliens usually do not have natural enemies, they are able to disperse easily and are good opportunists and find an empty ecological niche which they can occupy. They often manage to make a foothold in stressed areas such as disturbed land and agricultural land. The shrub tobacco (tabakk tas-swar), another introduced species, is common in building rubble.

Many species of plants which have become part of the Maltese countryside were not always present. Carob, fig and almond trees have been in Malta since antiquity. The prickly pear was introduced in the 16th century for its fruit and as a hedge plant.

Some plants such as the castor oil tree can become problematic weeds. This species which has striking large leaves and small greenish flowers was probably imported as an ornamental plant and now grows in valley watercourses where it competes with indigenous species.

This article was published in The Times on 03.02.2010