Isoetes azorica 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Isoetopsida Isoetales Isoetaceae

Scientific Name: Isoetes azorica
Species Authority: Durieu ex Milde
Common Name(s):
English Azorean Quillwort
Isoëtes azorica Durieu ex Milde
Taxonomic Source(s): Christenhusz, M. and Raab-Straube, E. von. 2013. Polypodiopsida. Euro+Med Plantbase - the information resource for Euro-Mediterranean plant diversity. (Accessed: 2015).
Taxonomic Notes:

There are no significant taxonomic issues associated with this name.

Assessment Information [top]

Red List Category & Criteria: Vulnerable C2a(i); D2 ver 3.1
Year Published: 2011
Date Assessed: 2010-05-24
Assessor(s): Lansdown, R.V.
Reviewer(s): Rumsey, F. & Bilz, M.
European regional assessment: Vulnerable (VU) C2a(i); D2
EU 27 regional assessment: Vulnerable (VU) C2a(i); D2
This species is classed as Vulnerable because it has an estimated range (here interpreted as area of occupancy) of 13 km². The maximum estimated population is under 10,000 individuals with less than 1,000 in each of the 11 subpopulations. Several threats, especially invasive species, pollution and eutrophication have led to population declines and are continuing to do so if no appropriate conservation measures are taken.

Geographic Range [top]

Range Description:This is an endemic species to the Azores (Euro+Med Plantbase 2006-2010) where it is found on the islands Corvo, Flores, Faial, Pico, Terceira and São Jorge. The total geographic range estimated for Isoetes azorica is only 13 km2 (Commission of the European Communities 2009).
Countries occurrence:
Portugal (Azores)
Additional data:
Lower elevation limit (metres):400
Upper elevation limit (metres):1000
Range Map:Click here to open the map viewer and explore range.

Population [top]


The total population of this species is estimated as 2,000 to 3,000 individuals by Schäfer (2005). This estimate might be a bit low but the total number of mature individuals as surely below the threshold of 10,000 mature individuals with less than 1,000 individuals in a subpopulation. In total there are around 11 subpopulations (F. Rumsey pers. comm. 2010).

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:2000-9999
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species grows exclusively in permanent or temporary lakes and ponds at around 400 to 1,000 m altitude. It is adapted to oligotrophic waters with low floral diversity and associated to Littorella uniflora. It can also be found in ponds and lakes with higher nutrient availability and diversity. Regarding to Habitat Directive listed habitats, it can be found in 3130 Oligotrophic to mesotrophic standing waters with vegetation of the Littorelletea uniflorae and/or of the Isoëto-Nanojuncetea (Commission of the European Communities 2009).
Systems:Terrestrial; Freshwater

Threats [top]

Major Threat(s): The main and increasing threats to the plant come from the spread of invasive macrophytes, pollution and eutrophication. The population at Lagoa do Negro, Terceira has been dramatically reduced (<70%) in under ten years by the arrival and spread of Sagittaria subulata (F. Rumsey pers. obs. 2010). One of the three populations on Flores has suffered considerable mortality very recently (2010) as a consequence of pollution leaching from a nearby tip (F. Rumsey pers. comm. 2010).
Further threats to the species are grazing; leisure fishing; the construction of paths and cycling tracks; canalisation, modifying structures of inland water courses and other human induced changes in hydraulic conditions; and introduction of disease (Commission of the European Communities 2009).

Conservation Actions [top]

Conservation Actions: This species is listed on Annex II of the Habitats Directive and under Appendix I of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention). There is no other information on conservation actions or needs available. As a minimum, the following tasks should be undertaken:
  • Assess the size of populations and establish a basis for monitoring to measure trends.
  • Compile information on the life history of I. azorica, with emphasis on dispersal and population or metapopulation dynamics.
  • Assess the risk from the various threats listed and potential for these threats to be controlled or eliminated.
  • Given the small size of the known populations, at least the main sites should come under legal protection.

Citation: Lansdown, R.V. 2011. Isoetes azorica. The IUCN Red List of Threatened Species 2011: e.T162270A5567022. . Downloaded on 23 August 2017.
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