Sunday, March 13, 2011

Davallia canariensis, the Macaronesian rhizomatous fern

It is a fern lover of light, mild temperatures and frost-free rather dry acid soil. Not support the shade or excessive moisture. Its rhizomes succulent full of water and nutrients help to withstand long periods of drought. I like living on rocks covered with moss and lichens and also as an epiphyte, especially oaks, holm oaks, cork oaks and laurel trees, as garoés, barbusanos, Viñátigo and laurels. Its adaptability also allows clear walls and colonize faial-heath. It ranges Galicia, Asturias, northern Portugal, Cadiz, Madeira and the Canary Islands. Belongs to the family of Davalliaceae and chromosome is 2n = 80. 

Several copies of Davallia canariensis growing in full sun among the stones of a wall of the Villa de Mazo on the island of La Palma. 

In Andalusia, Davallia canariensis is protected by law and the cork corkscrews respect it when found growing as an epiphyte on the cork. The image has its roots tucked between the ridges of cork. Photo taken in the Natural Park of Los Alcornocales in the Cadiz province near the town of Jimena de la Frontera. 

Davallia canariensis group on a wall of volcanic rock of Los Llanos in the island of La Palma. Are several fronds of endemic Polypodium cambricum ssp. macaronesicum. 

Davallia canariensis growing as an epiphyte on a Canary Island date palm, Phoenix canariensis, in the municipality of Barlovento north of the island of La Palma.

Davallia canariensis growing as an epiphyte on a high branch of Garoe, Til or Arbol-fuente, Ocotea foetens, in the lush Bosque de Los Tiles of the Island of La Palma.

This fern also lives in the forest clearings of faial-brezal, like the photo was taken in the town of Los Llanos de Aridane. 

Young Davallia canariensis with rhizome rooted in the moss on a rock of Monte Poiso Madeira Island. The rhizome of this fern grows on the substrate surface always, never shed, because moisture does not support. He needs to touch the air and light. Can measure up to 2 cm in diameter. From the bottom, which is in contact with the ground, sprouting roots that set the rhizome, which is growing and branching out so that it can form a small colony with multiple shoots, all from a single individual.

Details of previous rhizome paleas covered up to 12 mm long, lanceolate, glossy, hyaline and ciliate margin. As it grows and branches to form buds sprout fronds that can reach 50 cm in length, with the petiole as long as the blade, red-brown, paleae covered, darker at the base. The petiole is seen in the picture is green because it belongs to a frond still tender. It will darken as time passes. 

Davallia canariensis fronds with 3-4 pinnate blade, subdeltoid, glabrous, with the last order segments lanceolate or ovate-oblong, dark green, lighter in the tender fronds. 

Davallia canariensis sori, apical submarginal, at the end of the nerves, with cup-shaped indusium.

Sporangium of Davallia canariensis now empty after the dispersal of spores. .

 A long sporangiophore sporangium of Davallia canariensis, which serves as the umbilical cord. It consists of several tubular cells and binds the sporangium to the pinnules, which supplies water and nutrients the sporangiophore sporangium takes the ring, which has a function similar to the mammalian placenta and nourish the spores while growing inside the bag of the sporangium. 

Davallia canariensis spores oblong-reniform, hyaline, large, a beautiful lemon-yellow color.

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