Aruncus dioicus (Walter) Fernald, Buck's-beard
Account Summary
Introduction, neophyte, a very rare garden escape. A disjunct circumboreal species.
1947-55; MCM & D; woods at Lisgoole, Upper Lough Erne, just outside Enniskillen.
Meikle et al. (1975) recorded this in the Revised Typescript Flora as follows, "occurs as an escape at Lisgoole with Leucojum and Polygonatum multiflorum". This remains the only record of this large garden perennial occurring in the wild anywhere in Ireland. Unfortunately, we do not have a precise record date, but it falls between 1947 and 1955 at the latest – the period when Meikle and his co-workers were recording in the VC.
Although A. dioicus has been grown for decoration in gardens in B & I since at least 1633, it was not recorded in the wild in Britain until 1950 (D.J. McCosh, in: Preston et al. 2002). The Fermanagh record is thus one of the very first discoveries of the species outside gardens anywhere in these islands. The lateness of the first 'escape' date and the subsequent flurry of records from wild stations represented in the New Atlas occurring throughout Britain (mainly in N England and C Scotland), but apparently NOT happening in Ireland, requires further study and explanation.
As a native species, A. dioicus is confined to damp or shady places in mountain districts of temperate C & S Europe and SW Asia (from Belgium to N Albania, although absent from most of the Mediterranean basin), but present also in the Pyrenees (Tutin et al. 1968). It forms part of a circumpolar species complex also known as A. sylvester Koestel, of which it may be considered a Eurasian subspecies (Kurtto et al. 2004).
Growing up to 2 m tall, with very large, bi-pinnate leaves and producing very conspicuous, creamy-white, plume-like, much-branched, pyramidal panicles of small, 5 mm diameter unisexual flowers, A. dioicus is widely cultivated in gardens, planted in estate woodlands and occurs naturalised and established as far north as 64°N on the Atlantic coast of Norway (Kurtto et al. 2004, Map 3280). The inflorescence of the male plant is more showy than the female and thus is the much preferred cultivated form. Escapes often occur naturalised in woodland or by water and they can become very persistent. Being ± dioecious (New Flora of the BI), the species sets seed only if plants of both parents are present, which is an unusual circumstance in the wild, although known at a site in Dunbarton (Vc 99), and in another near Moulin in East Perth (Vc 89), both in Scotland (Clement & Foster 1994). Escaped populations, however, are almost always unisexual and reproduction is therefore vegetative, the stout, much-branched rhizome spreading to form clonal patches.
Threats
None.