Starfruit (Damasonium alisma)
Key Details
| Taxonomic Groups: | Vascular plant > flowering plant > Herbaceous plant |
| Red List Status: | Critically Endangered (Not Relevant) [CR(nr)] |
| D5 Status: | Included in the baseline Red List Index for England (Wilkins, Wilson & Brown, 2022) |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | (none) |
| UKSI Recommended Name: | Damasonium alisma |
| UKSI Recommended Authority: | Mill. |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | in Stroh et al., 2014 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | CR in GB & England. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | All current or recently extant sites in England have occurred following targeted conservation action. |
| Question 3: | At a landscape scale, would the species benefit from untargeted habitat management to increase habitat mosaics, structural diversity, or particular successional stages? |
| Response: | Yes |
| Justification: | Concerted efforts to restore commons & village greens within the range of this species through tree / scrub clearance, re-excavation of 'ghost' ponds, & restoration of extensive grazing could resuscitate lost populations & maintain extant ones. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 6. Recovery solutions trialled |
| Recovery potential/expectation: | Low - Policy conflict (detail in comments) |
| National Monitoring Resource: | Combination - insufficient |
| Species Comments: | Formerly in over 50 sites in England, the species has declined to near extinction today, & has only been maintained through concerted conservation action (incl. some introductions). The species favours shallow pools on commons & village greens, where a long continuity of traditional grazing maintained an open, mildly fertile acidic clay substrate, clear oligotrophic waters & lack of competition from coarser grasses, forbs & scrub/tree growth. Seed appears to remain dormant for 100 years +, and a number of colonies (Naphill Common, Esher Common) have been restored through major pool clearance - though it can prove very difficult to maintain suitable conditions subsequently. Issues for future grazing arise through difficulties in fencing registered commonland, though new no-fence technology may help here. |
Key Actions
Key Action 1
Proposed Action: Research into what causes “boom and bust” cycles at (re)introduction sites and how self-sustaining populations can be created. This will entail manipulating variables and recording total number of plants, effective seed pod production, & site conditions (incl. openness of pool substrate, vegetation structure, presence of invasive grasses, forbs & scrub/trees, & any ongoing management). Review management requirements as necessary.
Action targets: 5. Remedial action identified
Action type: Scientific research
Duration: 3-5 years
Scale of Implementation: ≤ 10 sites
High priority sites: All
Comments: Damasonium alisma fluctuates wildly from year to year, so annual monitoring is necessary (recognising that conservationists should assess for trends in population over time). Monitoring data needs to inform conservation action.
Key Action 2
Proposed Action: Maintain grazing & other vegetation management at sites where species still persists, & consider creation of new waterbodies within grazing units to allow natural or assisted spread within sites.
Action targets: 6. Recovery solutions trialled
Action type: Habitat management
Duration: 3-5 years
Scale of Implementation: ≤ 10 sites
High priority sites: Black Park. Stoke Common. Mole Gap to Reigate Escarpment -.
Comments:
Key Action 3
Proposed Action: Undertake feasibility of all sites where D. alisma has been recorded since c. 1900 to establish whether habitat management and sustainable long-term management can be introduced to restore extinct populations of species from soil seed bank. Undertake works where possible.
Action targets: 6. Recovery solutions trialled
Action type: Habitat creation
Duration: >10 years
Scale of Implementation: ≤ 10 sites
High priority sites: Naphill Common SSSI. Esher Common SSSI. etc.
Comments: Restoration of 'lost' populations from buried seed has been demonstrated at multiple sites over the past three decades (e.g. Naphill Common, Esher Common, Littleworth Common etc.). However, it is the long term ongoing management of these populations that prove so difficult, as each requires significant tree removal & restoration of grazing. Conservationists need to review values of reinstating lost grazing regimes to our south-eastern commons & undertake long-term programme to restore such sites.
Acknowledgment:
Data used on this website are adapted from Threatened species recovery actions 2025 baseline (JP065): Technical report and spreadsheet user guide (Natural England, 2025). Available here.