large greasewort
Aneura maxima
Photo: Photo: (c) Helen Waterman, some rights reserved (CC BY), uploaded by Helen Waterman
Overview
The large greasewort (Aneura maxima) is a thalloid liverwort in the family Aneuraceae, distinguished from its more common relatives by its notably broader, fleshier thallus. Like other members of the genus, it lacks differentiated leaves, instead forming flattened, irregularly branched green ribbons that lie close to the substrate, often with a glossy, oil-rich appearance characteristic of the family. This species is classified as Critically Endangered (CR) on the IUCN Red List, placing it among the liverworts facing the most severe risk of extinction in the near term.
Aneura maxima occupies specialized, moisture-dependent microhabitats, typically growing on permanently wet rock surfaces, streamside substrates, or saturated humus in shaded, humid woodland settings where atmospheric moisture remains consistently high throughout the year. Its known range is highly restricted, with populations confirmed from only a small number of localities, reflecting both genuine rarity and the species' narrow ecological tolerances. Population trend data are currently unknown, underscoring a broader gap in monitoring for bryophytes relative to vascular plants and vertebrates.
Despite this uncertainty, there is a meaningful positive note: renewed botanical interest in liverwort taxonomy and habitat surveys in recent years has improved detection methods for cryptic thalloid species, raising the likelihood that overlooked populations of Aneura maxima could still be found and protected. Conservation of this species depends heavily on safeguarding the hydrological stability of its microhabitats, since even minor disturbances to shade cover or water flow can eliminate suitable conditions. As a Critically Endangered liverwort with a fragmented and poorly documented distribution, Aneura maxima exemplifies the urgent need for targeted bryophyte conservation within broader forest and watershed protection strategies.
Aneura maxima is primarily threatened by the loss and degradation of the consistently moist, shaded microhabitats it requires, particularly where streamside woodland is cleared or hydrology is altered by drainage or water abstraction. Because the species depends on narrow humidity thresholds, even localized disturbance such as canopy thinning or small-scale development near its habitat can rapidly render a site unsuitable. Its highly restricted known range leaves remaining populations acutely vulnerable to stochastic events and to cumulative pressure from land-use change in the few areas where it persists.
Habitat
Aneura maxima grows on permanently damp rock faces, streambanks, and saturated humus within shaded, humid woodland environments, where stable moisture levels are essential to its survival.
Other threatened species in Aneuraceae
Threatened in Australia
Frequently asked questions
Why is large greasewort classified as Critically Endangered?
Where does large greasewort live?
What are the main threats to large greasewort?
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