Evidence of pollination and seed set in Scottish populations of Spiranthes romanzoffiana: News from Aberdeen University and Plantlife Scotland

摘要

The nationally scarce orchid Spiranthes romanzoffiana (Irish Lady's-tresses) is restricted in Europe to only a few places in Ireland and the Western fringes of Scotland, and to one isolated population in Devon (see Preston et al. 2002), but is widespread in North America (Arft & Ranker, 1998) (see Colour Section, Plate 1). A complete lack of seed set has been reported from Scottish populations (Gulliver, 2005) and the cause of this reproductive failure is unknown. Vegetative reproduction in the formof twin lateral bud formation has been proposed as a means of reproduction for S. romanzoffiana in Scotland (Gulliver et al. 2006) and studies carried out in the West of Scotland have highlighted the importance of maintaining the correct levels of grazing to conserve vegetative plants and allow flowering to take place (Gulliver et al. 2003 & 2007). Both the Irish and Colonsay populations have been shown to have limited or zero genetic diversity with higher diversity reported from Coll, Barra and Vatersay populations (Forrest et al. 2004). However, without seed set, the potential for long term maintenance and recovery of this species is severely limited.