Ceratocapnos claviculata (L.) Lidén, Climbing Corydalis

Account Summary

Growth form and preferred habitat

C. claviculata is a delicately stemmed, much branching annual, whose branched leaf-tendrils give it a decidedly limited climbing, scrambling and trailing ability since the plant usually only extends up to around 80 cm or so in height. In terms of soil preference, it is markedly calcifuge in character. Most unusually for an annual species, its most natural habitat in the British Isles is in shady or semi-shade sites in rocky hillside glens, or sometimes along drier areas of scrub-lined river or stream banks. In such 'wild' situations, acidic mineral or peaty soils are well-drained by being on fairly steep slopes. Here, the plant typically scrambles amongst rocks and over other plants in half-shade or in the better light of clearings in deciduous woods, scrub or conifer plantations, especially when these are protected from grazing and disturbance. Sometimes it may also occur in gorse or other scrubby heath vegetation (again, particularly when they are protected from browsing), and it may occasionally be found on heathy hillsides or roadside banks that have become infested with bracken colonies or bramble patches (McMullan 1972; Chater 2010). C. claviculata becomes especially conspicuous after the associated woody species have been cut or burnt in order to harvest, control or regenerate heath or woodland vegetation.

Flowering

The plant flowers from June to September; the small flowers, borne in racemes of five to ten, are pale yellow or cream to almost white in colour and they produce nectar which attracts bees. They are, however, self-compatible and probably mainly self-fertilising (ie they are autogamous) (Clapham et al. 1962; Jonsell et al. 2001).

Seed dispersal

The fruit capsule produces between two and four seeds which (depending on the authority cited) may (Stace 1997), or may not (Jonsell et al. 2001) possess a fleshy aril or elaiosome food body. The latter attracts ants and possibly other animals and appears adapted to effect some degree of seed dispersal. An interesting project would be to clarify the true position regarding the existence of a seed oil body and, if one does exist, to arrive at an estimate of the distance ants (or possibly snails, or birds) transport the seed (Ridley 1930).

Fossil record

Again, as with Pseudofumaria lutea, I am not aware of any fossil record for this species. I believe that there are very few fossil records for the related Fumaria species, some only at the generic level only, and most or all of these are associated with sites of human settlement or cultivation (Godwin 1975).

Fermanagh occurrence

There is a solitary recent record of this rare casual in the Fermanagh Flora Database as listed above. The overgrown derelict garden of an abandoned dwelling of architectural interest contained an interesting collection of around 30 weeds, some of which, like this species, are rare, unusual or seldom found and recorded in Fermanagh, or indeed elsewhere in most of Ireland. Since the Fermanagh record was made, the house has been restored and reoccupied and therefore it is very likely that the garden has also been brought into cultivation and the species ousted.

Irish occurrence

Mackay (1836) described the species in his book Flora Hibernica as occurring, "on rocks, walls, and on tops of old thatched houses". He mentions stations occurring for instance, "on thatched cabins between Ballinteer and the little Dargle (river)", and by "the wayside" (ie under hedges or on hedgerow banks), "between Dundrum and the Dublin mountains".

At the end of the 19th century, Colgan & Scully (1898) described C. claviculata as occurring, "chiefly in the counties of Dublin and Wicklow, with two out-stations in Waterford and Donegal". Three years later, Praeger (1901), who had meantime found an additional station for the plant upstream from Waterford on the River Barrow in Co Kilkenny (H11), was writing of C. claviculata as being, "a plant of the SE, with one outlying station in Donegal". With the addition of two further localities in the south-centre of the island in N Tipperary (H10) (McMullan 1972), this still remains very much the position taken in the Census Catalogue of the Flora of Ireland by Scannell & Synnott (1987). The latter reference lists the plant as Corydalis claviculata, which the authors regard as indigenous and recorded at least once in seven Irish VCs, not at that time including Fermanagh.

The couple of records of C. claviculata that exist in the north of Ireland, including the old Culmore, Co Donegal record of Hart (1874), and another northern 1988 record in a cleared plantation wood in Co Monaghan (Alan Hill, pers. comm., January, 1990), on examination appear decidedly synanthropic. They were found growing either close to or upon dwellings, or occurring as garden weeds or in estate plantation woods. Since the earliest mentioned Cos Dublin (H21) and Wicklow (H20) stations also fit this pattern closely, I believe there definitely is a case for describing C. claviculata as a naturalised, neophyte alien throughout Ireland. It was probably introduced with soil on the roots of garden plants and plantation tree stocks, most likely during the late 18th and early 19th centuries.

British occurrence

In Great Britain, C. claviculata is widely dispersed throughout the island and is locally common in the west. Although it is chiefly a lowland plant, it does reach 430 m in S Northumberland (VC 67). Despite the amount of forestry plantation that has gone on across Britain since 1970, the distribution has remained stable when compared to that in the 1962 BSBI Atlas. It is, however, better recorded now than previously was the case (Walters & Perring 1962; P.J. Wilson, in: Preston et al. 2002).

European occurrence

Beyond Britain and Ireland, the distribution of C. claviculata is restricted to W Europe, ie it is endemic to that region (Hultén & Fries 1986, Map 894). The species extends in a slightly disjunct, discontinuous manner from N Portugal along the Atlantic coastline to W Norway, reaching its northern limit just beyond 60N. The European distribution closely overlaps that of heathland in W Europe (Gimingham 1972) and the perimeter of both these distributions fits well with Koppen's (1918) 'Cfb', ie a constantly moist and mild 'Oceanic' type of climate.

C. claviculata is regarded as indigenous in Denmark and populations are expanding, encouraged by the plantation of conifers. The species is also considered indigenous in coastal parts of S Norway. Elsewhere in Norway, however, established alien populations are known to occur. Furthermore, in S Sweden, Climbing Corydalis arrived in the late 1950s and is now recognised as an established alien variously transported along with imported timber, with Rubus shrubs, or as a weed amongst other horticultural stock. It already occurs in S Sweden as a garden escape (Jonsell et al. 2001).

Names

The genus name 'Ceratocapnos' is a difficult combination to decipher, and it does not really appear to make much sense. 'Keras' is Greek for 'a horn', and 'capnos' (or in Greek, 'kapnos'), means 'smoke'. The latter is possibly a reference to its related genus (and family name), 'Fumaria', which is reputed to comes from the Mediaeval Latin 'fumus terrae', meaning 'smoke of the earth', a supposed reference to the diffuse (perhaps, smoke-like), foliage of some members of the family. Another possibility is reference to a supposedly smoky, irritating smell the plant is said to give off (Stodola et al. 1992). The Latin specific epithet 'claviculata' means 'having tendrils', the reference here being to the tendrils of the Vine and also to the branched tendril resembling a small key (Gilbert-Carter 1964).

Threats

None.

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