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Cirsium heterophyllum (L.) Hill, Melancholy Thistle

Account Summary

Possibly native and possibly neophyte, very rare. Eurosiberian boreal-montane, introduced in N America.

15 July 1949; Carrothers, E.N., Davidson, R.C. & Taylor, P.; hay meadow by the Roogagh River.

June and July.

Growth form, reproduction and preferred habitats

This large, distinctive, robust, unarmed (not prickly), perennial thistle has a woody rootstock and can produce stout, cottony, furrowed, branched flowering stems up to 1.5 m tall. As in C. dissectum (Meadow Thistle), C. heterophyllum is rhizomatous (or forms subterraneous stolons (Sell & Murrell 2006)); either way it sends out horizontally spreading vegetative underground stems to form more or less dense, clonal clumps or patches. This is again, as in C. dissectum, very probably the main means of species reproduction and population persistence. This is said on account of the apparent total lack of data on seed production, dispersal and plant establishment from seed in this species.

The basal leaves of the plant are long-stalked and very large (up to 40 cm long), elliptic-lanceolate, finely toothed, but like the rest of the plant, not armed with spines to deter herbivores. The large leaves are shiny and almost hairless above, but abundantly felted with floccose, cottony white hairs beneath, so that even in the vegetative state the plant could not be mistaken for C. dissectum, the leaves of which are dull and hairy above (S. Smith & C. Rimes, in: Stroh et al. 2019). Stem leaves are few; they clasp the stem and their margins are either entire or ± toothed, lanceolate, with white and cottony undersurfaces (Melderis & Bangerter 1955).

In common with C. dissectum, the established strategy of C. heterophyllum is categorised by Grime et al. (1988, 2007) as SC/CSR, meaning it is intermediate between a Stress-tolerant Competitor and a more equal balance of all three basic strategies, Stress-tolerator, Competitor and Ruderal species.

C. heterophyllum favours fairly moist, damp or wet places in unimproved pastures, hay meadows, roadside verges and on damp, grassy, hill slopes, often too steep to permit safe access for agricultural machinery (Hutchinson 1972). It also frequents the sides of mountain streams, moist, upland scrub and open areas in damp montane woods or on their margins. Having said the above, C. heterophyllum has also been recorded arising from the shade of grykes in limestone pavement, a rather drier habitat than most others it frequents (P. Stroh, in: Stroh et al. 2019).

Melancholy Thistle belongs along with Geranium sylvaticum (Wood Crane's-bill) and Trollius europaeus (Globeflower) to a group of associated boreal tall herbs characteristic of northern birchwoods in Scandinavia, and subalpine larch woods, clearings and herb-rich hay-meadows in the Alps and other southern mountain ranges (Clapham 1978). In phytosociological, NVC terms, the damp, herb-rich grassland community it often occupies seems to be closest to the Geranium sylvaticum sub-community of the U17 Luzula sylvatica-Geum rivale tall-herb association, and the herb-rich birchwood, which it may possibly have developed from the Crepis paludosa sub-community of W9 Fraxinus excelsior-Sorbus aucuparia-Mercurialis perennis woodland (Rodwell 1991a, 1992). It also appears in the few surviving upland herb-rich hay meadows that the NVC lists as MG3 Anthoxanthum odoratum-Geranium sylvaticum grassland.

C. heterophyllum reaches its highest altitude in Britain at 760 m in the Breadalbane mountains in Mid Perthshire (VC 88), in E Scotland (F.H. Perring, in: Preston et al. 2002).

Flowering reproduction

C. heterophyllum flowers from June to August. The flower-head (ie capitula) is usually solitary, but occasionally there are several and they then form terminal clusters of 2-4, borne on a bare, spineless and wingless, furrowed, erect stem. Each capitula usually measures 3.5-5.0 cm in diameter and is several times larger than those of C. dissectum, making them quite unmistakable. The numerous, appressed, involucre phyllaries are narrow, entire, glabrous, green and purple in colour, the outer ones with a mucronate apex (ie a short, abrupt tip). The flowers are all bisexual and are of one kind only (Hutchinson 1972). The florets are 40 mm long and are red-purple in colour, the upper portion of the corolla longer than the lower, slender tube. The heavyweight flower-heads initially droop sideways, rather sad looking on their tall, slender, white-haired stems. It is thought that this melancholy appearance gave rise, by the 'Doctrine of Signatures', to the herbalist use of the plant to treat melancholy (see below) (Grigson 1955, 1987).

When the capitulum is mature, the flowers are held upright rather than hanging pendulous and they attract mainly bees as pollinators. The achene fruits, 4 × 2 mm, are ovoid in shape, striate or smooth, fawn or brown in colour, and with a distinct apical collar. They are topped with a long, white pappus of hairs that carries the seed on the wind for dispersal (Butcher 1961; Clapham et al. 1987).

There is only one record of C. heterophyllum seed longevity in the survey of soil seed banks of NW Europe and it suggests the species is ephemeral (ie survives in soil for less than one year) (Thompson et al. 1997).

Possible toxicity

As C. heterophyllum, like C. dissectum, is without physical, spiny armament to defend itself against herbivores of all types and sizes, yet both these species manage to persist in grazed meadows, it seems quite likely that they might possess some toxic or disagreeable chemical compounds sufficient to deter browsing herbivores. The only evidence the current author (RSF) can find for this possibility is the suggestion that various members of the family Compositae (or Asteraceae), including Cirsium and Carduus species, are known to accumulate nitrates in potentially toxic amounts (Hibbs 1979). However, no reports of their having caused poisoning to stock animals have been found (Cooper & Johnson 1998).

Fermanagh occurrences

This thistle has persisted for at least 70 years in the two damp hay meadows where it was found in 1949 by Carrothers, Davidson and an English botanist from Kew, Mr Peter Taylor, the first record of this species in Ireland (Carrothers 1949). Carrothers et al. (1950) gave a fuller account of this most interesting find, describing a stand of, "over 50 flowering plants (healthy and vigorous, some over 5 feet [1.5 m] tall), accompanied by an even greater number of sterile plants. The majority of the plants found grew close to the steep river bank, although several flowering specimens were also noticed towards the centre of the damp meadow.". A few more flowering plants were found, "in an adjacent meadow higher up the stream" (Carrothers et al. 1950).

Meikle and his flora recording group found a second separate site in 1950, a mile [1.6 km] further down the Roogagh River (Revised Typescript Flora). RHN and the current author (RSF) have not been able to relocate this additional site, despite very careful searching in fields along the river on several occasions. In 1993, the two of us counted about 40 plants in a 10 m square at the known site, and another 20 plants in the same meadow some distance from the first clump. In June 2005, there were a total of 16 plants in two groups: only two individuals were in flower. In June 2009, plants were found in four groups in the corner of the field, approximately 6-10 m from the riverbank.

Species native status and conservation

Carrothers et al. (1950) saw no sign of introduced or alien vegetation in the vicinity of their first site, which is a heavily grazed meadow area, and he and his flora recording companions felt certain that C. heterophyllum was indigenous in this locality. The current author (RSF) and RHN would like to concur with this view and regard the species as a relict of a former, more herb-rich vegetation. It is not impossible, however, that seed might have been accidentally imported, perhaps with fodder, or along with animals purchased from Britain, making it a neophyte.

In NI, the species is listed for conservation protection under Schedule 8 of the Wildlife (NI) Order, 1985, and the meadow site at Roogagh River, which is also rich in orchid species, is designated an ASSI. C. heterophyllum is also included on the NIEA list of Priority Species of special concern requiring local conservation action.

A possible additional Fermanagh record

A further record for C. heterophyllum has recently come to light in the notes of the late Miss Norah Dawson, who was BSBI VC Recorder for Co Armagh (H37) for many years. In July 1976, she recorded Melancholy Thistle in the N of the county, E of Formil forest, "a stand of about 100 plants near a group of C. palustre [Marsh Thistle], in a drier part of a section of wet, cut-over bog". While this record was made by a very well respected field botanist and has therefore the real possibility of being a correct identification, no voucher specimen appears to exist and it requires confirmation before it can be wholeheartedly accepted.

Other Irish occurrences

A small number of apparently casual occurrences of C. heterophyllum have also been recorded elsewhere in Ireland; one in 1962 by a roadside at the E end of Lough Gill, Co Leitrim (H29), recorded by the famous Scottish botanist, Mary McCallum Webster, a BSBI Recorder for three VCs (Banff (VC 94), Elgin (VC 95) and Easterness (a portion of VC 96), who died in 1985. No mention of this site occurs in the Irish Red Data Book and the current author (RSF) and RHN presume that it has not persisted or been rediscovered. A few other reported sightings have proven to be mistaken. According to the Ulster Museum Flora Webpage, another record exists on the Armagh (H37) side of the Fermanagh boundary near Fivemiletown, but the RSF has found no details of it and therefore assumes it is an error.

British occurrence

The distribution of C. heterophyllum in Britain is almost the exact opposite of that of C. dissectum, such that it looks as if one species ecologically and geographically replaces the other (Perring & Walters 1962, 1976; Preston et al. 2002). C. heterophyllum has been recorded from as far south as Glamorgan (VC 41) in S Wales and the distribution spreads northwards from Radnorshire (VC 43) and Derbyshire (VC 57) to the tip of Scotland, including the Outer Hebrides (VC 110). It is considered an introduction in some of the Scottish isles, including Arran (VC 100), Orkney (VC 111) and Shetland (VC 112).

Interestingly, in its Derbyshire sites, it appears on the limestone at the extreme south of the Pennine Range. RSF remembers first seeing and being impressed by it on the limestones around Malham in W Yorkshire in the early 1970s, yet it is hardly a calcicole plant. Lousley (1969) commented that it appears to grow equally well on a wide range of soils, provided an adequate supply of moisture is available. It favours fairly wet places in pastures and on grassy hill slopes (Hutchinson 1972).

C. heterophyllum populations in Britain have been declining since the early 1960s (or even earlier, post-World War Two), due to changes in agricultural management and farm stocking, including, most significantly, the shift away from hay making towards silage, which has taken over to a very large extent so that fodder hay (eg for horses) has become a rare and expensive commodity. There have also been major changes in the breeds of cows used for milking and beef production, and fluctuations in the density of sheep grazed on higher ground and their 'wintering' on lowland meadows (Bradshaw 2009). Since the mid-1940s, many previously ancient herb-rich hay-meadows have been destroyed by ploughing and reseeding with faster growing, more productive grass varieties and grass-ley mixtures involving new clover varieties.

European and world occurrences

C. heterophyllum belongs to the Eurosiberian boreal-montane phytogeographical element and has a widespread, but disjunct, distribution in Eurasia, ranging from 71oN in Scandinavia southwards to Schleswig and Pomerania and to the mountains of C Europe, ranging across from the Pyrenees to Romania. In middle European latitudes, the species stretches far eastwards into C Russia and Siberia. Melancholy Thistle is recognised as an introduction in N America and as a rare introduction in both Iceland and S Greenland (where it rarely flowers) (Böcher et al. 1968; Löve 1983; Hultén & Fries 1986, Map 1863; Clapham et al. 1987).

Uses

It was Culpeper (1653) who took the hanging or nodding immature flowerheads as the 'signature' of the plant to mean that it would prove a remedy for melancholy. His herbal writing is filled with references to astrology (Henrey 1975) and he wrote of the plant, "It is under Capricorn, and therefore under both Saturn and Mars, one rids melancholy by sympathy, the other by antipathy. Their virtues are but few, but those not to be despised; for the decoction of the thistle in wine being drank, expels superfluous melancholy out of the body, and makes a man as merry as a cricket.".

Names

The specific name 'heterophyllum' means in Latin, 'diversely leaved', or 'other leaved', apparently referring to the fact that the basal and upper stem leaves are entire, while the leaves near the base are generally pinnately lobed. The previous specific name 'helenioides' was derived from the Greek, 'helodea', meaning 'marshy', or 'growing in marshy places' (Gilbert-Carter 1964).

Threats

Extreme rarity is always a threat in itself, but the Fermanagh landowner is aware of the plant and maintains a regime of cutting and grazing that allows the population to persist.

References

Carrothers, E.N. (1949); Carrothers,E.N., Meikle,R.D. and Moon, J.McK (1950); Meikle,R.D.(Ed.), Carrothers,E.N., Moon,J. McK. and Davidson, R.C. (1975); Lousley, J.E. (1969); Cooper, M.R and Johnson, A.W. (1998); Hibbs, C.M. (1979); Curtis, T.G.F. and McGough, H.N. (1988); Clapham, A.R., Tutin, T.G. and Warburg, E.F. (1987); Clapham, A.R.(Ed.) (1978); Grigson, G. (1955, 1987), Rodwell, J.S. et al.(a) (1991); Rodwell, J.S. et al. (1992); Gilbert-Carter, H. (1964); Culpeper, N. (1653); Henrey, B. (1975); Grime et al. 1988, 2007; Thompson et al. 1997; Melderis & Bangerter 1955; Butcher 1961; Böcher et al. 1968; Löve 1983; Hultén & Fries 1986; Hutchinson 1972; Perring & Walters 1962, 1976; Preston et al. 2002); Sell & Murrell 2006; Bradshaw 2009; Stroh et al 2019