Whitebeam (Sorbus Aria) Crann Fionnchoill Ted Cook

Likely our rarest, least encountered and taxonomically challenging of our native trees. Some might say Alder Buckthorn or Bird Cherry, both of which are legally protected.

The sudden exodus from Britain in 410AD of the Roman legions opened the gates to a vast immigration of German tribes, predominantly Jutes, Saxons and Angles. Modern spoken English is littered with Teutonic agrarian terminology – dyke, hedge, penn, wych (as in elm), weald (giving us forest and wealth), field, garden, fold and beam.

Beam, signifies ‘tree’ and with whitebeam’s unique, indeed startling foliage that catches the light like metallic silver, our sorbus is aptly named.

Excluding our rowan tree, in Ireland we have 5 indigenous whitebeam species of more shrub than tree, including an endemic and very rare Irish whitebeam, Sorbus Hyberna. The ubiquity of whitebeam within our suburban tame and leafy species masks the isolated and widely discontinuous distribution of these ‘races’ of native trees. One species, S. Aria tolerates elevated sulphur / air pollution levels.

When Karl Linné, son of a Swedish cobbler and inventor of our binomial system, published his scheme in 1735, he assigned S. Aria to whitebeam – the former being the plant’s Latin name, the latter, also whitebeam, deriving from a Latin already archaic in the 5th century.

Dinneen (1927) translates Fionncholl (white hazel) as wych elm – our modern scholars opt for whitebeam – with its very fine grained and heavy wood that furnished our forest forbears with cooking spits of exquisite workmanship – and to accompany the ritual hunt, the plump juicy fruits of the same tree accompanied venison.

All of Ireland’s whitebeam species are found on limestone or calcareous clays overlying such ‘old bone’ geology – Killarney’s limey Lough Leane, Passage East’s calcium rich deposits, the Burren’s interior, Lough Neagh’s eastern shoreline etc. – with our finest example of Sorbus forest (with Bird Cherry and Alder Buckthorn and carpeting Toothworth) to be found within Ireland’s largest remaining extant ancient woodland at Lough Ree on the Shannon.

A dioecious tree, some form full growth at 1.5 metre but generally reaching 9 metres – the crown unswept – with single simple large leaves with distinctly corrugated veins, 8 or 9 pairs, that flicker their white felted undersides eye-catchingly in the wind. On closer inspection, the white felt presents dense pale brown (hairs) – a strategy to reduce desiccation or moisture loss in the face of water robbing wind, acquired during the 150km per century journey from their refugia in glacial retreat times. Additionally, look out for markedly toothed leaf margins – within mild lobes in some forms.

Loosely clustered pale perfumed flowers that ripen into fruits – rosehip coloured on S. Aria, green- orange on others and green-scarlet on others, dispersed by birds in late autumn.

In France Sorbus had adapted to siliceous / acidic soils, enjoying the company of bilberry.

Likely due to geographical isolation and habitat fragmentation, S. hyberna has abandoned sex and perfected the art of apomixes – reproduction without fertilization i.e. progeny being genetically identical clones.

Page 1 of 2

Figure 1: Whitebeam (Sorbus Aria)

Page 2 of 2