In winter, large clumps of Mistletoe Viscum album can be seen from 100 metres away or more. You should, however, beware of being misled by rook nests and witch's-brooms, although the latter are most often on birch, which doesn't seem to host mistletoe.
December 2018. Lime green circles and orange squares: 1987-1999 Green circles and dark red squares: 2000-2019
The most frequent mistletoe hosts in Norfolk appear to be poplars (Populus spp.) and limes (Tilia spp.) but it is also quite common on apple trees (Malus spp.) and willows (Salix spp.); it is not unusual on hawthorn (Crataegus spp.) and occasionally occurs on False Acacia (Robinia pseudoacaia). Other hosts are rare. When you send in records it will be helpful if you can mention the host species.
Mistletoe is widely scattered in the county and there are still six 10km squares where it is yet to be re-recorded and several where it wasn't recorded between 1987 and 1999.