Sea Knotgrass (Polygonum maritimum)
Key Details
| Taxonomic Groups: | Vascular plant > flowering plant > Herbaceous plant |
| Red List Status: | Vulnerable (Not Relevant) [VU(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: | Polygonum maritimum |
| UKSI Recommended Authority: | L. |
| 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: | Assessed as VU in England (Stroh et al. 2014), & confined to c. 10 sites. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | A species vulnerable to natural changes in beach communities, but UK population numbers <1000 plants, so merits careful monitoring |
| 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: | No |
| Justification: | Confined to naturally-restricted open sandy communities above high water on sandy beaches |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 3. National Monitoring Plan agreed and implemented |
| Recovery potential/expectation: | Low - Policy conflict (detail in comments) |
| National Monitoring Resource: | Opportunistic - sufficient |
| Species Comments: | Species has increased rapidly in recent decades, perhaps due to climate change. But at continuing threat from recreational pressures on beach habitats, & possible increased storm activity. |
Key Actions
Key Action 1
Proposed Action: Undertake regular monitoring, to highlight changes in population sizes, & to be understand species demography
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Status survey/review
Duration: >10 years
Scale of Implementation: ≤ 10 sites
High priority sites:
Comments:
Key Action 2
Proposed Action: Implement programmes to protect key colonies from excessive visitor pressure etc, leading to damage to favoured open foredune vegetation. Sites without P. maritimum, yet within natural range of species should be protected, allowing development of assemblage of rare species (e.g. Euphorbia peplis, Atriplex laciniata etc) from waterborne seed or buried seed bank.
Action targets: 5. Remedial action identified
Action type: Pressure mitigation
Duration: Unknown
Scale of Implementation: National
High priority sites:
Comments:
Key Action 3
Proposed Action: Seed material from all extant native sites should be collected under licence for 'banking' in the Millenium Seed Bank, for future reintroductions etc, as necessary
Action targets: 6. Recovery solutions trialled
Action type: Ex situ conservation
Duration: 3-5 years
Scale of Implementation: Unknown
High priority sites: All native extant populations
Comments: Whilst populations may reappear in large numbers from buried seed after long absence, populations can be rapidly lost, as the species is vulnerable to excessive human disturbance (e.g. beach visitors) and natural processes. Maintenance of back-up material under ex situ conditions therefore important.
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.