The current status of the rare Scottish endemic Hieracium drummondii Drummond’s hawkweed (Asteraceae)

The records of Hieracium drummondii Pugsley, Drummond’s hawkweed, (Asteraceae) are reviewed. It has been recorded from eight general localities and it not accepted in four others. Seven of the eight localities have been visited but only one population of 20-25 plants was found at Crinan. It is IUCN Threat Category ‘Critically Endangered’ and is on the verge of extinction.

It was first described by H. W. Pugsley from material collected by Tom Drummond at Linn Mill, Clackmannanshire in 1876 (Pugsley, 1948). Pugsley listed it from Linnell [Linn Mill] and Aberdona in v.c.87 West Perth and from Careston in v.c.90 Forfar. Sell & West (1968) mapped it in six hectads including additional sites in v.c.84 West Lothian, 98 Argyll and 101 Kintyre. McCosh & Rich (2011, 2018 mapped it in 11 hectads including additional records from v.c.73 Kirkcudbrightshire and 94 Morayshire. As part of a project to collect seeds of rare endemic hawkweeds for the Millennium Seed Bank, Royal Botanic Garden Kew, I attempted to collected seed of H. drummondii in 2016 and 2017 without success (Rich, 2018). This prompted a review of the records and further field survey in 2019, the results of which are presented below.
Hieracium drummondii is distinguished from the other British and Irish members of Hieracium section Foliosa (Fr.) Arv.-Touv. by the combination of dark styles, predominantly glandular-hairy, narrow 0.9-1.2 mm wide bracts and usually sparse to dense stellate hairs on both sides of the upper leaves.

Methods
Data were compiled primarily from herbarium material in BM, DUE, CGE, E, MANCH, NMW and RNG, many determined by P. D. Sell Webster (1978). In the absence of the voucher and in light of redetermination of her v.c.94 records above, this record is not accepted without a voucher either.
KiImartin -Ford road junction (v.c.98 Argyll) Hieracium drummondii was collected at the Ford-Kilmartin road junction (some databases cite it incorrectly as a cross roads), NM842011 by A. G. Kenneth on 27 August 1961 (CGE). The grid reference refers to a patch of woodland NW of the junction with heavily shaded stream-sides and a salmon farm. The stream-sides, road junction, verges and adjacent woodland edges were searched on 8 July and 29 Aug 2017 without success.
Crinan (v.c.101 Kintyre) Hieracium drummondii has been recorded in about four sites around Crinan (Cunningham & Kenneth, 1979). A. G. Kenneth first recorded it in good quantity on the roadside up the steep hill from the Crinan Canal north basin at NR787942 on 20 August 1960 (CGE). The following year on 11 August 1961 he recorded it on the roadside by the Crinan Canal about a kilometre SSE at NR790931 (CGE). J. N. Mills collected it from cliffs above the road, NR787944[5] at Crinan Hotel (MANCH). J. N. Mills and A. G. Kenneth collected it on 8 August 1968 from walls and rocks at NR788943 (this probably equates to the first site) and also nearby from grassy banks above road, NR786941 (MANCH). This latter site is probably where A. G. Kenneth also collected it 'near road fork' on 28 August 1969 (CGE).
These four sites and adjacent areas were searched 8 July and 29 Aug 2017 without success, the cliffs above the hotel are now covered with dense rhododendron and the roadsides are managed. Finally on 13 August 2019 a small population of 20-25 H. drummondii plants with a few H. strictiforme plants was found on the sea wall below the Crinan Hotel at NR78889446 (herb. TR, herb. McCosh) (Fig.1).
Barr Glen (v.c.101 Kintyre) Cunningham & Kenneth (1979) listed H. drummondii for 'Barr Glen: near Muasdale' (NR63); the record is also listed as 1953 Atlas of the British flora 10-km square mastercard. No voucher has been traced (assuming the 1953 Muasdale shore record below does not relate to this site) and this site has not been revisited.
There are two records (Cunningham & Kenneth, 1979)   However, even within Pugsley's species concept there is variation. The original material from central southern Scotland (e.g. Linn Mill and Aberdona) forms a uniform set of robust plants with glandular-hairy heads and leaves stellately-hairy on both sides, but material from elsewhere is more varied. The material from Eigg is relatively slender and looks different to the other material but fits Pugsley's concept, but a similar slender specimen from SE of Carloway (v.c.110) has predominantly glandular heads (cf. H. drummondii) but is otherwise H. strictiforme (E).
This rare Scottish endemic is on the verge of extinction. Of the eight confirmed localities in seven hectads, seven localities have been searched and it has only been found in one small population at Crinan, and is thus confirmed as IUCN (2001) Threat Category 'Critically Endangered' (McCosh & Rich, 2018). It could persist in some former localities but has not been refound (it took three attempts to refind it at Crinan) and could be in other sites as yet undiscovered. It is hard to say why it has declined, there being much potentially suitable habitat still present in most localities.