A floristic survey of Fair Isle II: new and notable records and the status of Euphrasia

Fair Isle is a small island of 768 hectares located half way between Orkney and Shetland. In the previous publication of Quinteros Peñafiel et al. (2017), we provided a complete flora for the island. This note updates the status of the Fair Isle flora subsequent to the survey by including corrections, new finds and other notable records.


A species list of Euphrasia
Work has begun to decipher the range of Euphrasia taxa across the island. Euphrasia taxa are renowned for being taxonomically complex and therefore difficult to identify, with Fair Isle plants being particularly problematic for three reasons. First, plants are often extremely dwarfed by the environment and are also lateflowering, thus falling outside the phenotypic range typical of species. Second, habitat heterogeneity and extensive roadside disturbance create the conditions for complex genetic mixes that would rarely be encountered in more discrete environments. Third, the small geographic scale and relatively small population sizes of some species means mean that unusual morphotypes can become abundant. The latter point is particularly notable on Fair Isle, with our field observations revealing plants with unusual dark-pigmentation of vegetative parts, as well as plants with fused floral parts (see Fig. 2). These represent odd morphological varieties not known from other localities. Collectors should also be aware that extensive sheepgrazing often causes damage and induces atypical branching patterns. Our species identifications proposed below follow our current understanding of Euphrasia taxonomy outlined in the BSBI Handbook on Euphrasia (Metherell & Rumsey, 2018).
Further morphological studies are required to clarify the identity of the complex coastal taxa, including complex genetic mixes. We also hope that the use of genetic approaches (Wang et al., 2018) and common garden experiments (Twyford et al., 2019) will help clarify the distinctiveness of Euphrasia species on Fair Isle. We have identified putative hybrids following the definitions in the Euphrasia handbook (Metherell & Rumsey, 2018), but with the knowledge that many of these plants may not actually be of hybrid origin. There are some very good examples of true hybridity on Fair Isle but in other cases, plants may show unusual variation found within a species, or be dwarfed forms stunted by local conditions. Alternatively, they may be more complex genetic mixes such as backcrosses.
Our Euphrasia arctica x nemorosa: present along a roadside in the south of the island. Plants present a range of morphological variation including that close to E. nemorosa.
Euphrasia confusa x foulaensis: found in sheltered grassland proximal to the coast. In addition to highly branched E. foulaensis (described above), some plants demonstrate narrow corollas, with subacute leaf apices, leaf teeth longer than wide, and some short capsules, all typical of E. confusa.
Euphrasia foulaensis x marshallii: occasional, though likely to be overlooked in the frequent areas of sympatry between these two common coastal species.
Euphrasia foulaensis x micrantha: found in a complex roadside swarm of mixed affinity in the north of the island.
Euphrasia foulaensis x ostenfeldii: adjacent to the E. ostenfeldii population on Ward Hill. Similar to E. ostenfeldii, but almost glabrous and with long capsules.
Euphrasia micrantha x scottica: locally common, including near the Airstrip and Burn of Wirvie.

Concluding Remarks
The survey of 2016 (Quinteros Peñafiel et al., 2017) built on the pioneering work of renowned Shetland botanist, Walter Scott -sadly deceased in 2018 -and gave a modern assessment of the flora. The current update outlines gains since then. They reveal some of the means of arrival on the isle and the failure or otherwise of colonisers to establish. Despite a history of botanical interest and the small size of Fair Isle, recent finds also demonstrate how easy it is to overlook diminutive species. Interest in the island's vascular plants remains high and benefits from visiting botanists, observant members of the Fair Isle population and a resident observer (the lead author) who has provided continuity from 1981 to the present, allowing some reflection on short-term as well as long-term change. Many of the recent arrivals are clearly generated by indirect or direct human activities and relate to plants which do not persist. With climate-driven environmental change much in people's minds, Fair Isle is in a strong position to monitor the impacts; which include prospects of gains -e.g. plants establishing which previously were not able to adapt to local conditions -and of losses.
In light of changes since 2016, the Fair Isle vascular flora list stands at 260 UK native species (plus 71 UK aliens). The total number of species known to be present in 2019 comprised 235 UK natives (and 42 UK aliens).