Flora
The Maltese islands, with their central Mediterranean location, are characterised by a flora which has affinities with the flora of the rest of the region, i.e. the western, eastern, and North African Mediterranean. The main resemblances are with the flora of Sicily (and in some case with that of the Pelagie islands).
There are over a thousand species of vascular plants, of which about 700 are indigenous, over 200 are introduced species, and a few (about 25) are endemic or sub-endemic. The endemics (which are hence particular to just the Maltese islands) are either palaeoendemics, which survived only on the islands following a southward migration after the Ice Age, or neo-endemics, species which evolved as a consequence of isolation. Sub-endemics all have a restricted distribution, such as for example plants that are found only in Malta and Pelagian Islands and nowhere else in the world.
These include the Maltese national plant (Palaeocyanus crassifolius), the Maltese cliff-orache (Cremnophyton lanfrancoi), the Maltese salt tree (Darniella melitensis) and the Maltese spurge (Euphorbia melitensis).
Alien Invasion in the Maltese Islands
When going around the Maltese countryside, one may find a large variety of trees and plants growing. Most people see no difference between one type and another, but to environmentalists there is a full-scale invasion happening right in front of our eyes.
Malta is lucky to be a biodiverse hotspot with over 1000 plant species recorded locally in our ecosystem. However, there has been an increase in alien species. These are species which are not native to an area and that have been introduced after the discovery of the Americas (circa 500 years ago). The majority of alien species do no harm to the environment and are often an excellent choice for urban greening. However, some species can become invasive. This is when they start reproducing and spreading on their own and start to take over. These cause huge problems for our local environment. They often outcompete local species for water, light, nutrients and space, resulting in the destruction of these species. The local species are also integrated in the local food chain and are important for several local animal species. With the decrease in food availability, such species also tend to decrease. These are some of the effects of invasive species, which Malta seems to have no shortage of.
When walking through the countryside, two of the most iconic sights are yellow carpets of Cape Sorrel (Ħaxixa Ingliża, Oxalis pes-caprae) and walls of prickly pear cactus (Bajtar tax-Xewk, Opuntia ficus-indica). However, neither of these are local species at all. They instead were imported from around the world and planted here, where they spread accidentally or through human intervention. The cape sorrel is native to South Africa and was first planted in the 1800s in a botanical garden in Floriana. From there it has spread all over Malta and subsequently Europe, partly from Malta’s export of orange tree stock. It is often speculated that the spread of this plant has led to the decrease and even extinction of certain local species. The prickly pear cactus on the other hand, was mostly spread by human intervention for its use in agriculture as a windbreaker, barrier marker and food source. Although it is not a particularly invasive species, it tends to dominate the landscape where it is planted and easily outcompetes surrounding plants resulting in damage to the ecosystem.
However, these are far from the only problematic alien species. The Castor Oil Tree (Rieġnu, Ricinus communis) is another notable example and is now extremely widespread across the islands notably in valley beds and disturbed ground. The multiple acacia species that were introduced mostly in the 60s are another problem. They often dominate the habitat they invade, outcompeting local species due to their hardiness and resilience. They have become a problem in many sites such as in Wied il-Qlejgħa (Chadwick Lakes) where areas of the valley now consist primarily of acacia.
Some species have only recently been introduced in Malta. Two suitable examples are the Fountain Grass (Pjuma, Penissetum setaceum) and the lead tree (Albizzja, Leucaena leococephala). The fountain grass was introduced as an embellishing plant in roundabouts and central strips from where it has spread. It has become a persistent problem in areas it spreads to and is incredibly difficult to remove. The lead tree has also been used in urban greening and in private gardens. From here it has spread in multiple areas where it continues to be a problem.
These species need to be eradicated from our islands before they can cause any further damage. They are near impossible to remove due to their resilience and often need heavy machinery or even pesticides to effectively cull their populations. Unfortunately, they are a very overlooked problem and not much is being done to remove them once and for all from Malta. Although several NGOs and environmental groups are doing their utmost to solve this problem, there are unfortunately not enough resources or man-power to fully take on such a task alone.
Sources:
http://www.maltawildplants.com/#:~:text=The%20biodiversity%20of%20plants%20on,rock%20pools%20and%20sand%20dunes.
http://www.maltawildplants.com/OXAL/Oxalis_pes-caprae.php
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0190237#:~:text=Oxalis%20pes%2Dcaprae%20L.%20is,invasive%20in%20the%20eurimediterranean%20area.&text=pes%2Dcaprae%20may%20have%20invaded,of%20the%2019th%20century.
https://www.cabi.org/isc/datasheet/37714
