This site and its content are under development.

Chaerophyllum temulum L., Rough Chervil

Account Summary

Introduced, neophyte, extremely rare and locally extinct. European temperate, very sparsely naturalised in eastern N America and New Zealand.

1902; Abraham, J.T.; roadside at Lisgoole, Upper Lough Erne.

Growth form and preferred habitats

Although C. temulum is rather similar in appearance to Anthriscus sylvestris (Cow Parsley), Rough Chervil is distinguished from all other umbellifers by the purplish patches, or almost entirely purple, rarely greenish, sometimes distinctly glaucous, hairy, solid (not hollow), angled stems that are slightly swollen below the nodes, and later by the mericarp fruits that are c 5 mm long, narrowing upwards, and dark brown with broad, rounded, lighter coloured ridges on them (Perring & Walters 1989; Sell & Murrell 2009; Jonsell & Karlsson 2010). A robust, tall, up to 100 cm high, rather hispid (hence 'rough') biennial, or rather, a monocarpic perennial (ie taking at least two, but usually more years to reach flowering capacity), C. temulum usually flowers later in the season than A. sylvestris – in June and July, and before Torilis japonica (Upright Hedge-parsley), so that these three umbellifers are not often confused (Grime et al. 1988, 2007).

Common and locally abundant in Britain, but rare in Ireland, C. temulum occupies the very same range of habitats as the more widespread A. sylvestris, namely on open ground at the edge of woods and in hedgerows, along disturbed, roadside verges and in rough grassland or open scrub (the latter particularly when near water). Also, it most often occurs on dry to damp, well-drained, moderately fertile and moderately acid to neutral or calcareous soils, in sun or half-shade (Garrard & Streeter 1983; Sinker et al. 1985). C. temulum has probably declined in Britain from the effects of eutrophication, which has led to a great increase in competition from species such as Galium aparine (Cleavers) and Urtica dioica (Stinging Nettle) (Braithwaite et al. 2006). The established strategy of C. temulum is described as CR (meaning Competitive Ruderal) by Grime et al. (1988, 2007), which suggests it can readily enough cope with moderate levels of competition in disturbed habitats, but nutrient enrichment greatly increases the level of stress it would face from the likes of G. aparine and U. dioica.

Fermanagh occurrence

There are only two records of this species in the Fermanagh Flora Database: the one dating from 1902 (listed above) and a second from another roadside at Cromaghy Lough in the 1945-53 period when Meikle and co-workers visited the county. The current author (RSF) and RHN firmly believe that in Ireland this is always a very rare species of marginal, rough ground habitats and a noticeable 'follower of man', which has become locally extinct in Fermanagh since about the 1960s.

Flowering reproduction

C. temulum flower heads include both male and bisexual (hermaphrodite) flowers and, again, like A. sylvestris, they attract as pollinators a range of unspecialised insects including beetles, flies and bees (Fitter 1987). Seed behaviour also follows the pattern of A. sylvestris, while longevity in the soil is described as transient or short-term persistent, ie survival is greater than one year, but less than five (Thompson et al. 1997). Germination after chilling to break dormancy, takes place chiefly in the spring.

Variation

Two varieties have been recognised in B & I by Sell & Murrell (2009). Var. temulum is a short plant with a slender rootstock. The lower stem has spreading, long eglandular hairs with short ones in between them, but never forming a dense clothing tomentum. The inflorescence usually contains up to eight umbel rays, rarely up to 12. This contrasts with the much rarer, probably introduced var. canescens (Benitez ex Thell.) P.D. Sell, where the plant is often tall and has a stout rootstock. The lower stem differs in having a covering of dense, short, white eglandular hairs; less hairy upwards. The inflorescence in this variety consist of up to 17 umbel rays. In Britain, var. canescens is only known from Cambridgeshire (VC 29) and appears to be an introduction from C Europe, probably transported recently with horticultural material (Sell & Murrell 2009).

British and Irish occurrence compared

The complete contrast between Rough Chervil's behaviour and status in Ireland and in Britain is both puzzling and rather astonishing. In England and Wales, C. temulum is widely distributed and very common to local in lowland areas, but in Scotland it is more or less confined to the coast, especially the E coast, and to the vicinity of the two large north-of-the-border conurbations. In Ireland, on the other hand, C. temulum is very rare and extremely thinly scattered throughout, with a slightly greater frequency towards the E, again possibly related to the marked anthropogenic character of this umbellifer, ie it demonstrates a strong association with greater levels of human disturbance in areas of dense urbanisation (New Atlas; Cat Alien Pl Ir).

There are parallel situations in numerous other species, including for instance in the same family, Clinopodium vulgare (Wild Basil). The most notable example of a major distribution difference in these isles is possibly the perennial Mercurialis perennis (Dog's Mercury). In each case, a common and widespread native British species is by comparison virtually absent or rare in Ireland and is considered an alien introduction. The current author (RSF) does not imagine that M. perennis is native anywhere in Ireland, although others, including Parnell & Curtis (2012), join Scannell & Synnott (1987) in suggesting it may be so in "one or two places in the Burren", Co Clare (H9).

Species comparisons

C. temulum and Anthriscus sylvestris are not only related, alike and appear in the same range of habitats, they also exhibit the same ecological tolerances and requirements as described by their Ellenberg Indicator Values (Hill et al. 1999). The fact that both of these umbellifers are chiefly found in linear, disturbed ground, roadside situations, preferably on basic, calcareous soils, makes the enormity of the difference in their Irish representation even more striking.

Species distribution differences like these are extremely difficult to comprehend, never mind explain! Surprisingly little is really known about plant species behaviour (ie the sum of their biology, ecology and local history). It is very difficult to predict a species' competitive ability in newly invaded territory, the consequent degree of success it may or may not have in maintaining a persistent colony, followed by effective dispersal from that spot to other available suitable sites, where it must again be capable of establishing viable breeding populations to achieve long term survival. Furthermore, insufficient data exist about the properties of this and many other wild flower species, in order to allow us to understand how they react to changes in the environment. Even a little more local natural history observation might help clarify matters in many instances where information is scarce or totally lacking.

Status and decline in Ireland

The situation becomes even more baffling when one realises that even as a naturalised introduced species, C. temulum has a previous history of somewhat greater prevalence in Ireland prior to 1945. Colgan at least recognised quite early on that Rough Chervil was probably a 'denizen', or only doubtfully native (Cybele Hibernica 1898). This necessarily subjective assessment has been widely accepted by the majority of Irish field botanists (eventually including even Praeger). Others reject this opinion, despite it being endorsed by Scannell & Synnott in their listing in the Cen Cat Fl Ir 2; other Irish local Floras, including for instance, Booth (1979) in Co Carlow (H13) and the entire sequence of six publications on the three county FNEI dating from 1888-1992 (ie including the three supplements published in 1895, 1923 & 1972), plus the Flora of Lough Neagh and Beesley (2006), all continued to unquestioningly consider C. temulum indigenous.

More detail on the distribution and decline of C. temulum in Ireland is possible from an analysis of the species map in the New Atlas. Firstly, this shows records from just 19 or 20 Irish VCs and only 11 Irish hectads have post-1986 records. A further two hectads have records from 1970-86 and 28 more can claim the plant during the pre-1970 period. The current author (RSF) estimates that there are around 1500 hectads on the New Atlas map of Ireland, making the present rarity and marked decline of C. temulum over a period of around 60 years very clear indeed (Preston et al. 2002).

The CEDaR Computer Database at the National Museums NI in Belfast holds a total of just 21 records of the species for the six VCs of NI, with dates ranging from 1837-1991. Sites in four VCs are listed from around Lough Neagh, but only the Co Antrim shore has a recent record of the plant.

Whatever its status, Rough Chervil has obviously been suffering a very slow, gradual decline towards extinction on this side of the Irish Sea. The decline of the species has taken place despite seed very probably being sporadically and accidentally re-introduced from time to time, in mud and in cargo that is transported on vehicles across the short sea crossing from Britain in vast quantities.

European and world occurrence

C. temulum belongs to the European temperate biogeographical element and its European distribution is similar to that of Aegopodium podagraria (Ground-elder), but it extends less far north, having only a few coastal localities north of 60°N in Sweden and Finland. It is regarded as only, "possibly indigenous in Denmark and S Sweden" by Jonsell & Karlsson (2010). It is absent from N Russia. However, C. temulum is present in most of temperate Europe, again becoming rare in the Mediterranean region, although it is recorded on Sicily, Corsica and Sardinia. It is also present in SW Asia and NW Africa. As an introduction, C. temulum is very thinly represented in E USA and in New Zealand (Hultén & Fries 1986, Map 1387; Sell & Murrell 2009).

Threats

None.