Fascinating plants between Earth and Sea

Seaweeds (in Latin Alga) are vegetal chlorophyll organisms, which can be aquatics and terrestrials.

Opposite to terrestrial plants, seaweeds don’t have any roots, flowers, stems, sheets.

They are organized in three parts:

  • The frond : the raised part of the seaweed;
  • The stipe : false stem which link the holdfast and the frond;
  • The holdfast is like the feet of seaweeds, it permits to stick on the rock for instance.
  • Those parts consist the thallus.
Photo prise au Trez-Hir (Plougonvelin) le 20 octobre 2016, par Julien Hageaux, Appareil Photographique : Canon EOS 600D

Photo takes in Trez-Hir (Plougonvelin) the 20 october 2016, by Julien Hageaux, with Canon EOS 600D

Brittany is the French country which shows the most important seaweeds diversity with 670 species!

Seaweeds are classified in 11 groups whose the three main are distinguished by the color: the brown seaweeds like the fucus, the green seaweeds like the “sea lettuce”, and the red seaweeds like the Chondrus crispus. Some seaweeds are associated with fungi and consist of the group of lichen (this “crusts” that we find on rocks…).

Les trois groupes majoritaires - Photo prise à Trégana (Locmaria-Plouzané), le 20 octobre 2016, par Julien Hageaux, avec l'appareil photographique Canon EOS 600D

The three main groups – Photo took in Trégana (Locmaria-Plouzané)

Reproduction is the main difference between seaweeds and terrestrials plants. Seaweeds have spores, that they disseminate to permit the growth of new seaweeds.

Like all plants, seaweeds have chlorophyll and can realize photosynthesis, by capturing light and CO2 dissolved in water, using all their surface, to make their food.

Every day, we consume seaweeds: they enter on the making of cosmetics (creams, shampoos …) and foodstuff (they can be ate directly or used has gelling agent). They can be also used as fertilizer or fuel. In the past, they were used on the making of iodine.

Seaweeds permit us…to breath! 50% of oxygen of our atmosphere come of seaweeds photosynthesis…



Citer ce billet
Julien Hageaux (2016, 1 décembre). Seaweeds. L'alguier d'Agathe de Gourcuff. Consulté le 27 mai 2024, à l’adresse

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