Common Quillwort
EN

Common Quillwort

Isoetes lacustris

UnknownLCEULCEU

Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Isoetes_lacustris

Overview

A detailed profile for this species is sourced from the IUCN Red List of Threatened Species as assessments become available.

Western Quillwort faces severe decline primarily due to eutrophication of its pristine lake habitats, as nutrient pollution from agricultural runoff and urban development promotes algal growth that blocks essential sunlight. Acidification from atmospheric pollution has degraded water chemistry in many Scandinavian and Scottish lakes where the species historically thrived. Climate change compounds these pressures by altering lake thermal stratification and extending growing seasons of competing aquatic vegetation.

Threat summary

Habitat

Western Quillwort inhabits the shallow margins and littoral zones of oligotrophic (nutrient-poor) freshwater lakes, typically growing in sandy or gravelly substrates at depths of 0.5 to 3 meters. The species requires exceptionally clear, unpolluted waters with stable pH levels and minimal nutrient loading, conditions found primarily in glacial lakes across northern Europe and Scotland.

TERRESTRIAL· major

Other threatened species in Isoetaceae

Spiny-spored QuillwortCR

Spiny-spored Quillwort

Isoetes echinospora

Unknown

Frequently asked questions

Why is Common Quillwort classified as Endangered?
Common Quillwort is classified as Endangered — facing a very high risk of extinction in the wild — because population numbers are declining steeply and key habitats are under sustained pressure. Western Quillwort faces severe decline primarily due to eutrophication of its pristine lake habitats, as nutrient pollution from agricultural runoff and urban development promotes algal growth that blocks essential sunlight. Acidification from atmospheric pollution has degraded water chemistry in many Scandinavian and Scottish lakes where the species historically thrived. Climate change compounds these pressures by altering lake thermal stratification and extending growing seasons of competing aquatic vegetation.
Where does Common Quillwort live?
Common Quillwort occurs in across multiple regions. Country-level distribution data is sourced from the IUCN Red List and cross-referenced with GBIF occurrences.
What are the main threats to Common Quillwort?
The main threats to Common Quillwort are ai-1, ai-2, ai-3, and ai-4. The full IUCN-classified threat record for this species is detailed on the species page.

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