Sunday, July 10, 2011
Notholaena marantae subsp. subcordata, the priestess of Sun God
Its love by the sun is perhaps the characteristic that more good defines to the Notholaena marantae, a strange hairy fern adapted to support the long months of persistent drought of the Macaronesian summer, the direct and intense irradiation of the sun of the noon and the burning torrid heat of rocks oriented to the south of the Canary Islands, the Island of Madeira and the Cape Verde Islands. The Notholaena marantae that lives in the Macaronesia belongs to the subcordata subspecies. It belongs to the Sinopteridaceae family with Cheilanthes and Pellaea. In the Canary Islands it is called Doradilla acanelada, by the showy hair color cinnamon that covers the underside of the fronds. Its diploid chromosome is 2n =58, n = 29.
I finished back leaving the precious town of Santiago del Teide and I arranged to raise towards the Tip of the Teide by a road full of curves, constructed on an old black lava river. They would be the 10 hours in the morning and the insolation was blinding. After a curve, to each side of the road, it appeared before my eyes of lover of the ferns a numerous population of Notholaena, Cosentinia and Cheilanthes, all of them worshippers of the sun and the heat, the antithesis of the idea that usually we have of the ferns, because on the contrary that the immense majority of them, these three sorts needs to live to total sun, with very little humidity, much heat and much light. I enjoyed as a child who had just given him the toy he likes. I parked in a small landing of the roadside ditch, removed my old compact camera that has accompanied to me in so many trips and I get ready to occur a stuffing of ferns. At the outset I only saw Notholaenas with its showy turgid fronds of more than 35 centimeters, but when I approached and watched between rocks and black stones they appeared numerous Cosentinia vellea with its shelter of white hair and small Cheilanthes pulchella, all of them with the fresh and turgescent fronds good in spite of the apparent dryness and the burning heat.
Vigorous Cosentinia vellea subsp. bivalens sharing the habitat with the Notholaena marantae subsp. subcordata. Extending the photos with a double click are better the details.
Old Cheilanthes pulchella, that keeps certain a similar one with the Notholaena, although their dimensions is much more modest and lacks the typical ferruginous pilosity in underside of their fronds. It grows in the same habitat, but it prefers more shaded situations. It is a Macaronesic fern, endemic of Canarias and Madeira.
Perhaps it was in the Island of La Palma where I could see the Notholaenas most vigorous with fronds almost 40 centimeters., growing in the low part of this retaining wall builded to retain the volcanic gravel and sand of a small hill near Teneguia Volcano located in the South end of the island. The sun was blinding and the temperature to the 13 hours of the noon had to go up to around 40ºC and nevertheless the Notholaenas and Cosentinias that grew there saw well turgescent and fresh. Made kneel on the gravel to do good photos to them I discovered its secret. The basaltic black sand that was behind the wall was humid, very humid, until the extreme to grow mosses and hepatic. Then I asked myself from where could come this humidity in a place so frightfully dry and inhospitable, more similar to a desert that to a Macaronesian island. I raised the eyes towards the hill of volcanic gravel and without stopping thinking I turned and scanned with the view the skirt of Teneguia Volcano that lowers towards the sea and then I understood the secret of that one mystery when seeing the peculiar plantations of vine that natives cultivated so intelligently in small holes excavated in the volcanic gravel. The humidity came from the marine breeze that every morning raises from the loaded humidity sea, hits against the very porous basaltic gravel that absorbs the drops of dew as a sponge and the freshest water little by little, drop to drop, are filtered towards the subsoil and dampen the roots of the ferns and the vines, giving them the life.
Next to this gorgeous Cosentinia vellea that grows in the skirt of Teneguia Volcano, to the left of the photo, we can see small thalli of hepatics and a little mosses on a showy humid sand. This condensation of the humidity of the marine breeze follows the same process that horizontal rain, so typical of the Macaronesia, replacing the leaves of the trees of the Laurisilva by the porous volcanic gravel.
In the Island of Madeira also grows the Notholaena marantae subsp. subcordata. Here we see a gorgeous unit near the city of Funchal.
Taking a walk by the long Footpath of the Pijaral, in the heat of Massive of Anaga, I was with this unit of pendular fronds, that at the outset I did not know what was, because in anything it was looked like a Notholaena. When I gave the return to a frond to photograph the sori and I saw ferruginous hairiness, I knew immediately that one was a solitary Notholaena born in a habitat little adapted for its species, perhaps of one spore taken by the wind. Their fronds downwards grew in a desperate attempt to catch the maximum of solar light, because right above there was a leafy forest of fayal-brezal that gave shade the most part of day.
This loving of the sun fern not always grows in places with constant water contribution throughout the year. These two units that live between rocks of the South skirt of the Tip of the Teide, far from the sea, must support to the long months of drought of the Tenerife summer without the contribution of the humidity of the marine breeze. But not probleme, although apparently seems dead and parched, its aspect is pure adaptation. When the soil where they are taken root is without water, rhizome reabsorbs the sap of the fronds, which are coiled on themselves and acquire the aspect of parched herbs. It is so his degree of dehydration that if a fronde with the hand is squeezed undoes between the fingers and nevertheless is not dead. With the first rains of the canary autumn, to the few hours the fronds are rehydrated, expanded, are unrolled, turned green again full of life as if nothing had happened. This adaptive mechanism is called aestivation.
Frond of Notholaena marantae subsp. subcordata with the bipennate, ovate-lanceolate lamina, reddish rachis and the whole or lobed sights in the base with the underside covered with paleae of an alive ferruginous or cinnamon color.
Detail of pinnae and pinnules of an alive more or less dark green color and peculiar off-white pluricellular hairs that arise from rachis and the beam of pinnae. Like the paraphyses of the Polypodium cambricum, these hairs would have the function of sensors of the environmental humidity and would indicate to the fern the optimal moment to open the sporangia and to disperse spores.
Detail of the pluricellular white hairs
Gorgeous cinnamon color of the paleae that cover the underside of pinnae and rachis.
Detail of the paleae of the Notholaena marantae, longer in rachis, that totally cover the sori with a protective shelter. Between the paleae also pluricellular white hairs grow, that as those of the beam of the frond, would have the same function to detect the environmental humidity degree, to disperse spores at the more adapted moment for their germination.
Microscopic image of a palea of Notholaena marantae.
Structure of a palea seen 400 increases. It is formed by the housings of dead and empty cells.
Sporangium of great size with a ring of close and very together cells.
Black very great and round spores with reticulated perispore.