Saturday, January 15, 2011
Ophioglossum lusitanicum, a small big champion
In appearance no one would say that it is a fern, since their tiny sterile fronds seem leaves of grass. Their habitat are the clears of Mediterranean scrubland whose clay soils moss-covered remain wet during the fall and winter. Their neighbors are the Cistus, several orchids, Pistacia, Asphodelus, Asparagus, rosemary, Phillyrea angustifolia, Gagea nevadensis, Crocus cambessedesii, wild olive trees, white pines, Brachypodium retusum, Plantago bellardii, Arisarum vulgare, Arum pictum, etc ...
Ophioglossum lusitanicum fall with 4 sterile fronds no more than 3 cm long and fertile fronds with immature sporangia. (Double click on the photo to enlarge)
Its life cycle is completed in about 7 months. During the dry and hot summers of Mallorca lies dormant in aestivation underground as small rhizomes, oblong or subglobose, brown, with thick roots, sometimes stoloniferous, so that over the years may be forming a little family around him through of underground stolons, each of which sprouts a new fern clone with the first rains of autumn.
Another fine specimen with a single sterile frond and a fertile frond with a stem at its apical end, formed by two rows of sporangia, in this case is still immature. Picture taken in late November.
Ophioglossum lusitanicum Group with small leaves resembling grass, which is easily confused with other herbs with which it shares habitat. These small leaves or sterile fronds sprout from the rhizome that is rooted deeply in the clay. In the picture looks as leverage to spring the soil cracks formed during the dry summer, which was cracked by the hot sun scorched Mallorca. When fertile fronds disperse the spores, they also take advantage of these deep cracks to germinate and thus be able to withstand the 5 or 6 long months of drought.
Detailed picture of the sterile frond thick, fleshy, linear-lanceolate or oblong-lanceolate, slightly fluted, to collect the morning dew and direct moisture away from the rhizome. Is also seen clearly how a crack exploit ferns soil to sprout, which saves them considerable energy, as well as their fronds do not have to go through the thick, hard clay soil. Ophioglossum are accompanying by the long filiform leaves and V-shaped grooved a Merendera filifolia, the tiny new shoots of mosses and liverworts several hatchlings of the species Oxymitra incrassata, quite abundant in the same garrigue, like lichen Diploschistes steppicus.
Each Ophioglossum lusitanicum can have from one to four sterile fronds and one or two fertile fronds, as the copy of the photo. The comparison with the tip of my index finger gives us an idea of the tiny size of the ferns. In this case the sterile fronds are less than 2 cms and fertile little over 3 inches.
Throughout the fall are sprouting new fronds accumulating energy to produce spores. Every morning, but no rain, dew moisture received, which is absorbed by the moss, which acts like a sponge, keeping the soil constantly moist clay. In early or mid-winter, depending on how early or late in the first autumn rains, it starts the maturation of sporangia and spore dispersal.
Stem with the two rows of mature sporangia initiated in February the dispersal of spores.
Each sporangium opens like a mouth with two lips and inside out transparent spores that fall close to his mother. If you are lucky and end up at the bottom of a small crack in the ground, germinate and give rise to the gametophytes, which produce and anterozoides oosphere. Once fertilization has taken place in the oosphere, created a new Ophioglossum lusitanicum the bottom of the crack. All this may take a couple of years and depends on a symbiotic fungus, probably of the genus Glomus, that mycorrhizal rhizoids of gametophytes of Ophioglossum and facilitates the production of gametes. This is mycorrhizae with arbuscular hyphae. The new true fern or sporophytes spring from a fertilized oosphere of mycorrhized gametophyte. Without this symbiotic fungus-fern, it is not possible to reproduce the ferns of the genus Ophioglossum.
Detail of the stem of a fertile frond with mature sporangia open like mouths, inside which the spores out aided by the wind and rain.
As if they were painted lips with crimson, the two halves of each sporangium open and disperse the whitish and transparent spores.
In this picture look better microscopic spores out of the sporangia. (Double click on the picture to enlarge)
Details of Ophioglossum lusitanicum spores, which have a concavity in form of fovea on one side. The photomicrograph is made with very little light because the spores are really transparent.