Saturday, May 19, 2012

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

No comments:

Post a Comment