Opposite-leaved Pondweed (Groenlandia densa)
Key Details
| Taxonomic Groups: | Vascular plant > flowering plant > Aquatic 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: | Groenlandia densa |
| UKSI Recommended Authority: | (L.) Fourr. |
| 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: | Species shows continuing decline. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | While the species would benefit from general improvement in water quality (and quantity), achieving its recovery at a reasonable timescale requires actions to be targeted at appropriate sites and water-courses. |
| 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: | This species would not benefit from untargeted management |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 5. Remedial action identified |
| Recovery potential/expectation: | Low - Policy conflict (detail in comments) |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | It is not clear whether current targets for improvement in water quality (e.g. by 2038 to reduce phosphorus from treated wastewater by 80% and from agriculture by 40%) will be sufficient to reduce the risk of this species' extinction by 2042 (i.e. in line with the Government's commitment to halt nature's decline). Nonetheless, targeted action will reduce the likelihood of the species' status worsening. |
Key Actions
Key Action 1
Proposed Action: Identify all those water management catchments where the species has been recorded over the last four decades. Of these, select at least 10 catchments for delivery of action, taking into account the rate of loss (aiming to target those catchments showing the greatest decline in frequency over the last 4 decades), and the potential for improvement in water quality and waterway management to lead to local recovery of the species.
Action targets: 4. Autecology and pressures understood
Action type: Status survey/review
Duration: 2 years
Scale of Implementation: ≤ 100 sites
High priority sites:
Comments: It is not clear how much of this work may be possible using pre-existing data, and how much would require site visits.
Key Action 2
Proposed Action: Across those catchments identified under action 1, deliver programmes of locally-targeted action to improve water quality and, where appropriate, water-course management
Action targets: 5. Remedial action identified
Action type: Pressure mitigation
Duration: >10 years
Scale of Implementation: ≤ 100 sites
High priority sites:
Comments: There are likely to be cross-overs with other catchment improvement programmes.
Key Action 3
Proposed Action: Carry out periodic monitoring of a sample of sites, based (for example) on the BSBI's Threatened Plants Project in order to gauge local population change and threats and to provide an assessment of the success of actions 1 and 2.
Action targets: 5. Remedial action identified
Action type: Targeted monitoring
Duration: 1 year
Scale of Implementation: ≤ 100 sites
High priority sites:
Comments: To be repeated every 5 years.
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.