Wednesday, 7 April 2010

Mistletoe: Parasite or beneficial, medicine or poison?

Our garden has some one dozen fruit trees, after the previous use as an orchard by a commercial farmer.  Most of the orchard is ‘infected’ with mistletoe.
Mistletoe is the name of a hemi-parasitic plant  that grows attached to and within the branches of a tree or shrub.  The word 'mistletoe' (Old English mistiltan) is of uncertain etymology; it may be related to German Mist, for dung and Tang for branch, since mistletoe can be spread in the faeces of birds moving from tree to tree. However, Old English mistel was also used for basil.

Life cycle
Mistletoe plants grow on a wide range of host trees, and commonly reduce their growth but can kill them with heavy infestation.  Almost all mistletoes are hemi-parasites, bearing evergreen leaves that do some photosynthesis, and using the host mainly for water and mineral nutrients. However, the mistletoe first sprouts from bird faeces on the trunk of the tree and indeed in its early stages of life takes it nutrients from this source.
Most mistletoe seeds are spread by birds, such as the Mistle Thrush in Europe.  They derive sustenance and agility through eating the fruits and nuts (drupes). The seeds are excreted in their droppings and stick to twigs, or more commonly the bird grips the fruit in its bill, squeezes the sticky coated seed out to the side, and then wipes its bill clean on a suitable branch. The seeds are coated with a sticky material called viscin which hardens and attaches the seed firmly to its future host.

Ecological importance
Mistletoe was often considered a pest that kills trees and devalues natural habitats, but was recently recognized as an ecological keystone species, an organism that has a disproportionately pervasive influence over its community. A broad array of animals depends on mistletoe for food, consuming the leaves and young shoots, transferring pollen between plants, and dispersing the sticky seeds.
A study of mistletoe in junipers concluded that more juniper berries sprout in stands where mistletoe is present, as the mistletoe attracts berry-eating birds which also eat juniper berries. Such interactions lead to dramatic influences on diversity, as areas with greater mistletoe densities support higher diversities of animals. Thus, rather than being a pest, mistletoe can have a positive effect on biodiversity, providing high quality food and habitat for a broad range of animals in forests and woodlands worldwide.

Medicinal use
Mistletoe leaves and young twigs are used by herbalists, and it is popular in Europe, especially in Germany, for treating circulatory and respiratory system problems. Use of mistletoe extract in the treatment of cancer originated with Rudolf Steiner, the founder of Anthroposophy. He compared the parasitic nature of the mistletoe plant to that of cancer, and believed that cancer represents a faltering of the body's spiritual defences. Som mistletoe preparations are diluted homoeopathically. Mistletoe extract is sold as Iscador, Helixor, and several other trade names. As mistletoe is a poisonous plant that causes acute gastrointestinal problems including stomach pain, and diarrhoea along with low pulse, we here at Homelands question the wisdom of using those alternative practitioners…  You certainly will not find it on our breakfast table!

Other uses
The sticky juice of mistletoe berries was used as adhesive to trap small animals or birds. In South Africa it is called "Bird lime" in English and ‘voelent’ in Afrikaans. A handful of ripe fruits are chewed until sticky, and the mass is then rubbed between the palms of the hands to form long extremely sticky strands which are then coiled around small thin tree branches where birds perch. When a bird lands on this it gets stuck to the branch and is then easy to catch by hand.

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