"Temporary Ponds: a natural habitat to be protected!"


> Isoetes setaceum


Like other Isoetes, it is a flowerless plant that reproduces through spores instead of seeds.

The leaves are grouped on the top of the short underground stem, which has no phyllopodia.

This species can be quite large and, under favourable conditions, the leaves can reach a length of 40cm.

At the basis of the leaves the sporangia are not covered by any membrane.

Sporos of Isoetes velatumI. histrix and I. setaceum, respectively
(Photo of Ivan Carvalho)


Isoetes setacea is a perennial Hydrophyte (Geophyte), characteristic for temporary humid zones and can support water levels of up to 50 cm.

The species is restricted to temporary ponds on quaternary basalt. It is found in Mediterranean aquatic quillwort swards, communities with Isoëtesspp. in fluctuating water bodies (Corine biotope 22.3412).

The vegetative growth generally takes place in winter while the maturation of the spores takes place in spring. It is a typical plant of temporary ponds and it colonizes the most central areas. It is adapted to long periods of submersion, up to 7 or 8 months.

Isoetes setacea is a west Mediterranean species. It is found in France (Hérault, Orientals Pyrenees), Spain (centre and west of the country and in Catalonia), the Balearic Islands (Minorca) and Portugal (centre and south).

In North Africa, it is limited to Morocco where it has been recently discovered in only one locality (Benslimane) with an area of occupancy smaller than 1 km².

In the Mediterranean region, the extent of occurrence is 530,000 km². The area of occupancy has not been quantified but may be less than 2,000 km² as the species is restricted to a particular type of habitat - Mediterranean Temporary Ponds.

 Rhazi, L. 2010. Isoetes setacea. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 24 August 2015.

In Portugal the distribuition is highly fragmented.

The populations are known to be declining due to the deterioration of the habitat.

Isoetes setaceum has only a small area of occupancy (less than 2,000km2) and it is experiencing a decline in population size, but it is not severely fragmented and occurs at more than 10 locations. It is classified as near threatened owing to its fragile habitat, temporary ponds, that is under much pressure from agricultural and infrastructure development as well as land abandonment.

This plant is a bioindicator species of the priority habitat 3170* of the Habitats Directive 92/43/CEE.

It has the status of Near Threatened species in the Red List of the International Union for Conservation of Nature and Natural Resources (IUCN).

Rhazi, L. 2010. Isoetes setacea. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 24 August 2015.

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