Friday, November 11, 2011

Cheilanthes pulchella emigrated to the Macaronesia to survive

Its genes remained in Europe and Africa in its daughter hybrid

The Cheilanthes pulchella genes were not prepared to withstand the cold and drought of Late Miocene. Before starting the last million years of this geologic time is living happily in Western Europe and North Africa with a warm and humid subtropical climate. There was hybridized with the Cheilanthes maderensis and its union had emerged a stronger and allotetraploid hybrid better adapted to changing climate, the Cheilanthes guanchica.

Cheilanthes pulchella photographed in full sun on the volcanic rocks of Santiago del Teide in Tenerife in early May. With it sharing the same habitat were numerous Cosentinia vellea and Notholaena marantae, two ferns also love heat and sun.

The Cheilanthes pulchella is one of the better adapted Sinopteridaceae to heat (thermophilia) and direct sunlight (heliophilia). Its roots are deeply embedded in the volcanic gravel with its porous structure absorbs and retains moisture from the sea breeze and provides the Cheilanthes pulchella all the water it needs.

Cheilanthes pulchella group in the Puerto de Izaña in Tenerife of about 2000 meters. along the road from the Pico del Teide to the town of Arafo. The sun's rays affect the fronds that extend into the light without fear of being burnt, protected as they are known for their excellent hydration provided by the roots.

At the onset of the Messinian salinity crisis in Late Miocene, the climate changed dramatically becoming more arid and cold and the Mediterranean Sea almost completely dried up becoming a desert with some very salty lakes. During that such adverse million years the Cheilantes pulchella died away from north to south and from east to west unable to withstand the cold steppe and the lack of rain. The seabed had emerged out of the water to lower the level of seas and oceans in about 100 meters and had become Western Europe, North Africa and the islands of Macaronesia in a continuum that facilitated the exchange of plant and animal species .

The Cheilanthes pulchella take this opportunity to spread its spores to the Macaronesian region where its descendants found a warm and humid climate more suitable for their survival. In the western Mediterranean and especially in the south of the Iberian Peninsula were its daughter genes in hybrid, the Cheilanthes guanchica, while its mother fled to the subtropical paradise of Madeira and the Canary Islands. The adaptability, hardiness and hybrid vigor of Cheilanthes guanchica allowed to colonize not only the western Mediterranean but also the Macaronesia, accompanying its mother on its flight to the southwest.

Frond closely ovate-oblong and tripinnatisect with its striking red rachis. The petiole, also red, is slightly longer than the blade.

Apex of a frond with typical linear-lanceolate and integerrimous pinnae, ie, whole or undivided with smooth edge without teeth or lobulations. These are followed by other apical pinnae somewhat lobed at its base.

Underside of a frond with sori protected by a continuous and comprehensive pseudoindusium striking that almost completely covers the underside of the pinnules. The rachis of the lamina, the pinnae and pinnules have a nice blood red.

Details of Cheilanthes pulchella pseudoindusium formed by a sheet of transparent cells born in the edge of each pinnules that it is folded inward and covers the sporangia that are located on either side of the rachis of the pinnules. When the spores are ripe, the pseudoindusium rises to allow the sporangia that are deployed as small catapults and disperse the spores as far as possible from their mother.

In this picture the pseudoindusium already fully raised, showing mature sporangia appear black balls. Each sporangium like a womb around a group of spores.

The ferns genus Cheilanthes contain various toxic substances, especially ptaquiloside and thiaminase, which cause in livestock that consume serious illnesses ranging from incoordination and somnolence to enzootic hematuria and polioencephalomalacia that they usually end up killing the animal. Its toxicity is a defense mechanism to protect themselves from predation by herbivores.

No comments:

Post a Comment