Sunday, March 11, 2012

Romulea assumptionis, tiny and coquette

La pequeña Romulea assumptionis es un endemismo tirrénico de la família de las Iridaceae. Vive en las Islas Baleares y en las Îles d’Hyères cerca de Marsella. Crece en los claros de las garrigas mediterráneas iluminados por el sol del mediodía. Comparte su hábitat con jaras, lentiscos, brezos, bruscos, esparragueras, gamones, aladiernos, merenderas, gageas, albaidas, fenazos, romeros, aulagas, olivillos, orquídeas, acebuches, encinas y pinos carrascoThe small Romulea assumptionis is a Tyrrhenian endemism of the Iridaceae family. It lives in the Balearic Islands and the Îles d´Hyères near Marseille. It grows in the clear ones of Mediterranean garrigues illuminated by the sun of the noon. It shares its habitat with Cistus, Pistacia, Erica, Ruscus, Asparagus, Asphodelus, Rhamnus, Merendera, Gagea, Genista, Brachypodium, Phyllirea, Rosmarinus, Calicotome, some orchids (Ophrys, Orchis, Serapias, Barlia) and some trees like Olea europaea subsp. sylvestris, Quercus ilex subsp. ilex amd Pinus halepensis.

 Romulea assumptionis photographed in March the last day of the winter in a garrigue of the center from Majorca to about 210 msnm. The substrate where its bulb is taken root is made up of argillaceous and calcareous soil cover by a layer of mosses and lichens that absorb the humidity of the dew and transfers it to the ground facilitating the survival of the small Romulea. The bulb is tiny. It measures between 7 and 10 millimeters.

The botanist Juan Rita Larrucea, professor of the University of the Balearic Islands, after studying this species in depth could verify that the Romulea assumptionis indifferently grows on coastal grounds very droughts like those of Marina de LLucmajor, on more humid calcareous-argillaceous grounds of the interior of Majorca like the one of the photo, on sandy ground in the peninsula of Arta and on water substrates even saturated in the high Majorcan mountain. The variations in the substrate do not alter their phenotype that in all the habitats is always equal. 

Until it does few years was considered a strictly Balearic endemism, but in April of 2004 a group of French botanists, studying the flora of Îles d’Hyères, found a Romulea with an atypical phenology very similar to the Romulea columnae that at first made think them about a possible hibridization. Nevertheless later they discarded this possibility when stating that, while the present units of Romulea columnae in the islands already were releasing the first seeds, this Romulea was initiating the flowering with a clear chronological separation of two months between both flowerings, which made its hibridization impossible. For more information on the finding I recommend to consult this article: 

Lateral vision of previous Romulea assumptionis. Its unique flower open in the end of a stem that does not surpass the 11 centimeters. Usually it blooms since the end of March until May.

As I already said in a previous article (They adore to the God Sun), the Romulea assumptionis is an extreme example of heliophilia. The pollination of its unique flower depends as much on the diurnal insects that it only abre the tepals if its sensors of light detect sufficient ultraviolet rays incident on it. It knows that its pollenizers will only see its flower if this one is directly illuminated by the sun. The violet veins of their tepals orient to the pollenizers towards the reproductive organs of the flower where they find one small drop of nectar like prize to its invaluable contribution. Throughout the year the tiny Romulea is accumulating nutrients and energy in its small underground bulb with the unique purpose of producing a single flower and of assuring therefore the survival the species. It cannot squander energy uselessly nor it can put in danger to its descendants. Its small flower always is oriented towards the noon. If near it grow pines, olive trees or oaks that do shade to it during the morning, its flower patiently hopes solar rays of the noon to open its tepals. The cloudy days its flower remains closed until it improves the time. If it is able to be fertilized the first day, in the evening it is closed and no longer it returns open. On the contrary one it opens several followed days until securing its objective. 

The Romulea assumptionis flower is hermaphroditic, actinomorphic and erect. It measures between 8 and 12 millimeters. The tepals are white with violet veins and are united by their base having formed a tube. Stamens have yellow anthers and the unique pistil is white and finishes in three deeply bifid stigmatic branches with filiform divisions that do not exceed anthers.

The fruit is a capsule of 5 to 11 millimeters.

The Romulea sort is integrated by 90 species that are distributed mainly by the South and East of Africa, especially in Cape province (South Africa), where are 70 species, by the Southwest of Europe, Mediterranean region and Macaronesian region (Canary, Madeira and Azores). All the Romuleas is then Euro-African. Our small Tyrrhenian endemism makes 6 million years must have a distribution much greater than the present one. At the end of Miocene, during the Messinian Period, the Mediterranean Sea had been dried almost completely and the South of France and its small coastal islands like Îles d’Hyères, Corsica, Sardinia, the Balearic Islands, Sicily, Malta, the Iberian Peninsula, the Italian Peninsula, North Africa and the Macaronesian region formed an all continuous one with very little water separated that them, so that during the million years that one so dry period lasted the animal and vegetal species could expand their populations to all this vast region. When the Mediterranean basin returned to fill of water, the Tyrrhenian mountains became islands and the species were isolate. Thus the peculiar present distribution is understood of the Romulea assumptionis.

The leaves are filiform, very thin and acute, among 30 and 100 millimeters in length and less than 0´8 millimeters of width and are arranged in a single plane forming an arc over the earth as the blades of a fan. Its color is green-grayish with reddish tones. Its filiform leaves clearly differentiate it from the other species that lives in the Balearics, the Romulea columnae, whose leaves are flattened, wider and of intense a green color. 

No comments:

Post a Comment