Erica tetralix forms a dwarf shrub or undershrub up to 60cm in height, usually semi-prostrate, with numerous tortuous, ascending branched stems, which root at the base (Bannister 1965). Branches have short auxiliary shoots and the twigs are pubescent and purplish in colour (Clapham, et al. 1987). The leaves are greyish and the edges are rolled under, nearly meeting below and are downy above (Rose, 1981). The small surface area effectively regulates water loss by transpiration and these types of leaves are known as ericoids. The cell walls are thickened with lignin or silica and may contain appreciable amounts of tannins, resins and essential oils. These make the leaves unpalatable and indigestible to herbivores and also highly flammable in dry conditions. When burnt the plant regenerates from the rootstock. These characteristics are evolutionary responses to low levels of nutrients e.g. low levels of phosphorous on heathland soils (Webb, 1986). The flowers occur in clusters, are rose pink in colour or occasionally very pale or white, and are larger than those of E. cinerea. E. tetralix is either self- or cross-pollinated, or perhaps pollinated to a degree by small insects (Clapham, et al. 1987).