Botanical Treasures of the Holes Bay Path
- 19 hours ago
- 8 min read
DHBlog038 · A coastal nature park with an intriguing flora
Stephen Smith and Tom Smith (no relation) led two well-attended Dorset Flora Group events at Holes Bay during 2024 and 2025. Development and industrialisation have left their mark on this part of the Poole Harbour Site of Special Scientific Interest (SSSI) over the past 150 years but it remains a haven for wildlife [1]. More recently, foundation of the Holes Bay Nature Park by the Poole Harbour Commissioners, Dorset Wildlife Trust and the former Borough of Poole (now BCP) Council has helped guide management of this ecologically sensitive area while bringing locals and visitors closer than ever to its attractions.
From the botanist's viewpoint, Holes Bay offers a remarkably wide range of species within easy reach of a convenient shared-use path. Anyone with a copy of the Collins Wildflower Guide by Streeter et al. has already benefitted from this as it provided the source material for several botanical species illustrated within the guide by local artist and DFG member, Christina Hart-Davies. Certain aspects of the bay's development have encouraged a floral diversity that was traditionally absent, generating a novel and often eyecatching flora along the shoreline. Stephen has been recording this diversity for a number of years now [2,3], building on earlier surveys carried out by Bryan Edwards in 2001 for the Poole Harbour Study Group [4] and by Robin Walls in 2015.
2024
The two DFG events covered adjacent areas around the eastern and northern edges of the bay on land owned and managed by BCP Council. On 8th June 2024, fourteen of us met on a rather cool and cloudy morning on the rounded promontory near Sterte. This area hosts a wide bank of grassland and it was testament to its content that we spent the first 2 hours here, within about 30 metres of the starting point. So, a classic botanical walk!
We carefully made our way through an expanse of Oxeye Daisy (Leucanthemum vulgare) and were almost immediately upon many Bee Orchid (Ophrys apifera) and Common Broomrape (Orobanche minor). We also found a good number of Grass Vetchling (Lathyrus nissolia) in this area.
Nearby, one of the group found our star curiosity of the morning: Sulphur Cinquefoil (Potentilla recta), an attractive non-native perennial with a sparse distribution along the East Dorset coast and a first sighting for most of us. We found several plants, all with petals of canary yellow rather than pale sulphur, suggestive of a cultivar such as 'Warrenii'. This species was recorded here previously by Stephen in 2022 and interestingly long before that, further round the bay by Humphrey Bowen in 1991. It seems to be a long-term, naturalised inhabitant of the bay.
Realising that time was passing quickly, we walked a short way north and found good numbers of Pyramidal Orchid (Anacamptis pyramidalis) looking very fresh, along with frequent Corky-fruited Water-dropwort (Oenanthe pimpinelloides).
Along the rocky shoreline, Annual Beard-grass (Polypogon monspeliensis) was abundant. This species has a place on Dorset's Rare Plant Register and is a real feature of the area. A smaller species inhabiting the rocks and a good sighting for many of us was Sea Pearlwort (Sagina maritima).
The whole area proved to be an excellent place to brush up on clovers, trefoils and other small legumes. It provided a fine array of flowering examples including Hare's-foot Clover (Trifolium arvense), Hairy Bird's-foot-trefoil (Lotus subbiflorus), Hop Trefoil (Trifolium campestre), Hairy Tare (Ervilia hirsuta) and Kidney Vetch (Anthyllis vulneraria).
The 2024 event covered just 3 of the 10 recording areas defined by Stephen and yet we managed to record 115 plants in 3 hours, all within OS grid square SZ0091. These ranged from grassland species through coastal to scrub and woodland-edge species, reflecting the wide range of habitats present along this narrow strip between the dual carriageway and the rocky edge of the bay. The full species list can be viewed here:
2025
One year on and twelve of us assembled on an appreciably better day: 31st May was sunny and about 21°C. Tom and Stephen led once again, the aim being to cover some of the areas that weren't reached in 2024, i.e. the northern part of the bay where habitats include woodland, saltmarsh, beach and some small areas of grassland.
We met at Upton Country Park and headed down to the shoreline path near The Lookout bird hide and began botanising. Here in OS grid square SY9992, we recorded 117 plant species including Pignut (Conopodium majus), Hairy Buttercup (Ranunculus sardous) and, on the near edges of the saltmarsh, Sea Aster (Tripolium pannonicum), Greater Sea-spurrey (Spergularia media) and Sea-milkwort (Lysimachia maritima).
We then headed east and emerged from the country park into SZ0092. This section of the path has a narrow beach and sea wall on one side and scrub and grassland on the other.
Here, we recorded 85 species in the time available. The most notable of these was the rare Round-headed Club-rush (Scirpoides holoschoenus), its position marked and effectively protected by a boulder. This is an extremely scarce species in the UK, recognised as a native at only 2 sites, namely Braunton Burrows in Devon and Berrow Sands in Somerset [5]. At Holes Bay, it is regarded as an introduction of enigmatic origins, but nevertheless persisting at the same location with the aid of habitat management since at least 1991.
Other coastal plants seen here included Annual Sea-blite (Suaeda maritima) and Black Mustard (Brassica nigra). Our species lists for the two grid squares can be viewed here:
Time passed very quickly and on reaching a point roughly level with McDonald's at the southern end of Wessex Gate Retail Park, it was time to turn round and head back to Upton Country Park for a well-earned drink in the café.
Intriguing colonists
Around Holes Bay, one might expect to find species typical of coastal habitats or the light, gravelly soils of the Poole basin. These species are indeed well represented but the bay is now also home to several notable calcicoles including Bee and Pyramidal Orchid, Common Broomrape and Kidney Vetch. Why might this be?
Part of the answer must lie in the composition of the land supporting the relief road, which is entirely artificial. The road and its bank were part of a massive land reclamation and infilling project completed in 1988, replacing an extensive area of tidal mudflats and marshland [6]. As is common in such projects in the south of England, a primary component of the foundation was crushed chalk, chosen for its cost-effectiveness, strength and regional availability. In places, the soil along the eastern bank is particularly thin and the underlying chalk is revealed [3]. Indeed, parts of the surrounding grassland are now so convincing that they support scarce chalk-specialist fauna such as the Small Blue butterfly (Cupido minimus).
There are no records of Bee or Pyramidal Orchids from Holes Bay prior to the construction of the relief road but these species were in evidence by 1998 [8], so it is possible that they were introduced with the initial surface dressing. Historical details of the surface layer are hard to come by but the topsoil is known to have been imported and in one area south of the railway line, it received a general amenity seed mix at a distant point in time [7]. There are, of course, many other ways by which these and other species might have colonised the area. Transportation of seeds through the activities of animals, people or machinery are all possibilities but it may also be significant that the seeds of Orchids and Broomrapes are extremely fine and can be carried on the wind for considerable distances. A search of nearby records reveals that one potential source of Orchid seed is the site of the former Poole Power Station on the opposite side of the bay. Orchids were first recorded there in 2018 but may have escaped attention for a considerable time beforehand due to a lack of monitoring [7]. It is an older site, dating from 1946 but likewise it is founded on a deep chalk platform. Interestingly, this chalk was quarried from the former pit at White Mill near Sturminster Marshall, now part of the National Trust's Kingston Lacy Estate [9–12]. It is tempting to speculate that this offers a link to the calcareous species present in that part of the county.
Common Broomrape is another plant with tiny seeds but in this case, plants did not appear at Holes Bay until much later, around 2021. Its discovery may have been aided by a change in verge management but clearly, the grassland is still developing. The continued appearance of interesting new species suggests that the path and its verges could provide valuable biodiversity and a point of interest for local naturalists for many years to come.
Considerable thanks go to Stephen for proposing and co-leading these two absorbing and rewarding visits. At the time of writing, parts of the route have been sacrificed for the construction of a works compound for the Poole Bridge to Hunger Hill Flood Defence Scheme [13]. While these works are of great importance, one hopes that the botanical losses will be short-lived.
This article contains text by Tom Smith, expansion and additional research by Daniel Holloway, photos from Tom Smith, Jo Stephen and Mariko Whyte, and was edited by Daniel Holloway.
REFERENCES
1. Rance, E., Taylor, D., Lagden, B. & Bleese, B. (2019). Holes Bay Nature Park: ecology & human activity; Dorset Wildlife Trust. Link
2. Smith, S.F. (2023). Vascular plants of Holes Bay between the eastern gate of Upton Country Park and Sterte, April – June 2021. Holes Bay Nature Park Birds and Wildlife Report 2021; Holes Bay Nature Park, 2023; pp. 127–134. Link
3. Smith, S.F. (2025). The flora of eastern Holes Bay, 2000-2024. Holes Bay Nature Park Birds and Wildlife Report 2024; Holes Bay Nature Park, 2025; pp. 71–81. Link
4. Edwards, B.W. (2004). The Vegetation of Poole Harbour; Poole Harbour Study Group, Wareham. Link
5. Scirpoides holoschoenus (L.) Soják. In BSBI Online Plant Atlas 2020, eds P.A. Stroh, T. A. Humphrey, R.J. Burkmar, O.L. Pescott, D.B. Roy, & K.J. Walker. Link
6. Slade, D. (2019). Photos: How Holes Bay Relief Road transformed Poole. Bournemouth Echo, 13 February 2019. Link
7. Jez Martin, pers. commun.
8. Mariko Whyte, pers. commun.
9. Slade, D. (2014). Do you remember the twin chimneys of Poole’s power station? Bournemouth Echo, 15 October 2014. Link
10. Letter to Ralph Bankes, Esq., about various Estate matters, 1 Jul 1946. Bankes of Kingston Lacy and Corfe Castle Archive: D-BKL/E/H/1/6/2977. Dorset History Centre, Dorchester.
11. Letter from Wimborne and Cranborne Rural District Council about land at Whitemill, 23 Aug 1946. Bankes of Kingston Lacy and Corfe Castle Archive: D-BKL/E/H/1/6/3579. Dorset History Centre, Dorchester.
12. Correspondence regarding a chalk pit, Whitemill, 9-19 Feb 1952. Bankes of Kingston Lacy and Corfe Castle Archive: D-BKL/E/H/1/7/1468. Dorset History Centre, Dorchester.
13. Knights Brown Construction Ltd (2026). Poole Bridge to Hunger Hill Flood Defence Scheme. Link
