Midwinter and Christmas is a time when evergreens Norway spruce trees, holly, and ivy come into their own. Another evergreen at this time is mistletoe (Viscum album). Growing as balls of green leaves, high in trees, mistletoe was thought in medieval times to have magical properties and to aid human fertility. Even today a kiss is often claimed from someone underneath a sprig of mistletoe.
As a semi – parasitic plant mistletoe makes its energy through its leaves but acquires minerals from its host tree. The plants grow from very sticky seeds that have either been, wiped off the beaks of birds that have eaten the berries, or excreted and accidentally lodged in favourable spots amongst branches and twigs. Inevitably many seeds are wasted! Host trees are those with suitably soft bark including apple, lime, poplar sycamore and ash, but rarely oak. Mistletoe has distinctive forked stems, paired evergreen leaves, tiny wind pollinated green flowers (open February April) and white pearlescent berries (November December).
Geographically mistletoe will grow anywhere with the right mild, humid, lowland conditions. Especially high concentrations of it used to be found in apple orchards around the River Severn. Nowadays those populations have reduced along with British appple production, but there are some signs that areas where it grows today are slowly shifting – possibly due to climate change. Over the last 15 years more of it seems to be occurring in areas of southern England such as west of the Chilterns.
Many birds ignore the white berries – perhaps because of their stickiness, but others, particularly mistle thrushes happily eat them – indeed its the reason the mistle thrush acquired its name!
Blackcaps are also birds that like mistletoe berries and may be helping its spread. Blackcaps used to be summer migrants to Britain and not around to eat the berries. In the last 30 years though, some blackcaps from Germany are migrating westwards after the summer, and spending winters in Britain. They're able to survive in our slightly milder winters. Most of Britain's summer migrant blackcaps however still migrate south to Spain, Portugal and West Africa!