In a particularly poor nutrient environment, species have developed survival strategies specific for an exceptional biodiversity!

Cazaux-Sanguinet Lake until recently kept exceptional oligotrophic favouring the development of rare plants. In a particularly poor nutrient environment, species have developed specific survival strategies favouring a high biodiversity. A large number of these rare plants at the edge of the Lake protection at national, European or global level.
In 2005, surveys of some rare plants was made at the initiative of the SAN to the Natura2000 classification. Download these detailed, inventories certified by doctor Jean Laporte-raw, by clicking on the following link: FloreAttestation
Here are some of the rare plants of the edges of the Landes Lakes and, in particular, the Lake of Cazaux-Sanguinet.

Hover over a document for more details.


Name: Drosera intermediate – Drosera intermedia

Description: carnivorous plant of modest size that comes in the form of rosettes of leaves in the shape of small spatulas. The leaves are lined with reddish hairs ended by a brilliant secretion drop allowing the capture of small insects which are then digested by enzymes. Flowering from July to August.

Protection: European red list of IUCN (assessment 2013): NT
Drosera intermediate at Biscarrosse


Name: the Portugal Heath – Erica lusitanica

Description: species of Heath that can reach 1 to 3 metres in height and produces flowers in white bells or dew arranged in compact clusters. Blooms from February to March.

Protection: red list of the vascular flora of metropolitan France – 1 (2012): in (listed Member Erica) Red Book of flora threatened with France – Tome I: species priority (1995): V (listed Erica Member Rudolphi)
Portugal Heath at Biscarrosse


Name: sundew – Drosera rotundifolia-round leaf

Description: carnivorous plant that only grows in areas of bog. Only species of the genus Drosera to present rounded leaves, at the end of which the hair produce a sticky juice to trap insects. Hatching occurs from mid-June to late August and white flowers are arranged in small clusters.

Protection: European red list of IUCN (evaluation 2012): LC (listed Drosera rotundifolia)


Name: lobelia lobelia – Lobelia dortmanna

Description: perennial plant of 20-50 cm, semiaquatic, that can be exposed part of the summer. Its narrow leaves form a rosette at the base of the stem which is usually submerged. The flowers are bluish or Liliaceae, sometimes nearly white. They are few, pendulous and carried by a peduncle of five to ten millimeters.

Protection: red list of the vascular flora of metropolitan France – 1 (2012): seen (listed Lobelia dortmanna). European red list of IUCN (assessment 2013): LC (listed Lobelia dortmanna).
lobelia lobelia


Name: great moat – Ranunculus lingua

Description: great plant (50-120 cm) perennial big present branched underground stem in the shallow waters of the edges of lakes, rivers and streams. Flowers about 3 to 3.5 cm in diameter, yellow. Flowering takes place between June and August.

Protection: World red list of IUCN (assessment 2014): LC (listed Ranunculus lingua). European red list of IUCN (assessment 2013): LC (listed Ranunculus lingua)
Great moat


Name: floating water-plantain – Luronium natans

Description: perennial plant developing two types of leaves: from the submerged lower leaves arranged in a rosette and the floating leaves. Flowering from May to September produces white flowers with three petals floating on the surface.

Protection: World red list of IUCN (assessment 2013): LC (listed Luronium natans). Red list of the vascular flora of metropolitan France – 1 (2012): LC (listed Luronium natans). European red list of IUCN (assessment 2013): LC (listed Luronium natans).
Floating water-plantain

The Quillwort of Bory, plant endemic to the South West

An aquatic plant that is sensitive to pollution

The Quillwort of Bory (Quillworts boryana) is a small herbaceous plant, smooth and hairless. Its leaves are semicircular section, filiform, distributed in clumps of erect or discarded and a fairly straightforward green color. They are persistent, are renewed in the spring or early summer and measure between 5 and 15 cm in length.
Individuals gathered in colonies, which can be more or less dense and can reach some tens of square meters. The number of plants varies strongly from one colony to another.

The Bory Quillwort is aquatic, but can live temporarily out of the water, where the substrate remains damp. She is present at the edge of the acidic ponds at bottom flat and sandy and grows at a relatively low depth (10-50 cm). Highly sensitive to organic pollution of the environment, it only found in calm, pure and crystal clear waters.
It colonizes sands barefoot and poor in humus. The appearance and the accumulation of organic debris on the sand may lead to its disappearance and its replacement by more appropriate aquatic vegetation (water lilies and pondweeds including).

Water oligotrophic very little mineralized Plains sandy, characteristics of the Lake Cazaux and Sanguinet, meet the requirements of the Bory Quillwort and are one of the last places of presence of the plant. Indeed, the species is endemic to the South-West of the France. Although having been reported in different regions of Spain, several authors have questioned these data. These uncertainties seem linked to difficulties in taxonomic order, including variants of the species or subspecies level.
This extremely limited range, as well as threats related to human activities, make the very vulnerable Bory Quillwort. If it is not preserved, the Bory Quillwort is doomed to disappear.

An endangered plant that must be protected

Status of the species:
  • “Flora-fauna-Habitat” directive: annexes II and IV
  • Berne convention: Annex I
  • Species protected at national level by France (annex I)
  • Rating IUCN: World: vulnerable; France: vulnerable

Excerpt from the National inventory of natural, directed by the National Museum of natural history heritage:
‘[…] given the limited number of stations and its restricted range, this species deserves careful monitoring and responsibility for the France a strong commitment to its preservation. »
As indicated by the status of the species, the Bory Quillwort is a protected plant. Yet no action is currently for the species and stations where its presence has been confirmed are integrated in any protected area. In current stations, it would seem that of Bory Quillwort populations, although only very localized, are relatively stable. Nevertheless, since the beginning of the century, the disappearance of several stations (Souston, bed-and-mix, Aureilhan and Leon) caused a regression of the Bory Quillwort.

The main threats to the extirpation of the species are:
  • siltation resulting from eutrophication of waters;
  • trampling;
  • sports.
By observing the last inventories in particular, it seems that sites subject to trampling experienced the strongest decline in workforce.
Conversely, it is interesting to note that this case would seem able to colonize new areas when they are cleaned. It comes, for example, lakes of hunting to “tonne” (huts of the waterfowl hunting).
The main proposals for the preservation of the Bory Quillwort are therefore:
  • maintain the character oligotrophic waters avoiding priority inputs of phosphorus (element limiting);
  • maintain natural; hydraulic Dynamics
  • do not use herbicides;
  • limit traffic to the concerned sites.

A plant to fight the greenhouse effect

According to the studies of the IRSTEA (national Institute for research on Science and technology for the environment and agriculture), it would seem that the Bory Quillwort facilitates uptake of carbon in the soil, thus limiting the production of gas greenhouse.

An excerpt from the site of the IRSTEA:
For this study researchers were particularly interested in lawns formed by the isoetides aquatic heritage small sized plants that colonize Sandy substrates, among which we can find:
-lobelia lobelia, (whose Aquitaine Lakes represent the southern limit of their distribution in Europe)
-the Littorelle to a
flower – and the Quillwort of Bory (endemic, that is, its global distribution is restricted to the Aquitaine Lakes).
“We were able to demonstrate the key role played by these species in the regulation of gas emissions greenhouse”, explains Cristina Ribaudo, engineer of research at the centre Irstea of Bordeaux. A first! “So far, we know these plants from the botanical point of view (distribution, presence, etc.) and ecophysiological perspective (i.e. responses behavioural and physiological to their environment agencies), but no studies had been conducted at the community level;” still less compared to their interaction with the cycle of carbon and methane.”
One more reason to monitor and protect this unique species !