Isoetes stephanseniae
Overview
Isoetes stephanseniae, the granite quillwort, is a species of quillwort from South Africa, named for A. J. Stephansen, who discovered it in 1927.
Of very limited distribution, it is known to survive only as one population in seasonal pools over granite near Stellenbosch, where it is threatened by the encroachment of alien species and eutrophication from the sewage works on whose grounds it grows. Like other quillworts, it bears a tuft of leaves with distinctively sculpted megaspores. It is most similar to Isoetes capensis, the cape quillwort, which occurs in the same province; both hold their leaves at a 45-degree angle, unlike most South African quillworts which have leaves stiffly erect.
Isoetes stephanseniae faces severe threats from habitat destruction due to urban development and agricultural expansion in its limited range. The species is particularly vulnerable to water level fluctuations and pollution in the seasonal pools and wetlands it depends upon. Climate change poses an additional threat through altered precipitation patterns that could eliminate the ephemeral aquatic habitats essential for this quillwort's survival.
Habitat
This critically endangered quillwort is endemic to seasonal pools, temporary wetlands, and shallow aquatic habitats in Mediterranean-climate regions. It requires specific hydrological conditions with seasonal flooding and drying cycles that support its unique amphibious lifecycle.
Conservation measures underway
Other threatened species in ISOETACEAE
Frequently asked questions
Why is Isoetes stephanseniae classified as Critically Endangered?
Where does Isoetes stephanseniae live?
What are the main threats to Isoetes stephanseniae?
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