Thursday, 29 January 2009

An Urban Parasite

A plant parasite is a plant which grows on another plant and steals nutrients from it. Mistletoe (Viscum album) is a parasite which grows on a wide variety of trees both native and non-native. Strictly speaking, Mistletoe is a ‘hemi-parasite’, that is, it steals minerals and water from its host but it is also semi-evergreen and so manufactures some of its own food, through the process of photosynthesis, like other plants (1).
Mistletoe plants are either male or female. The tiny, yellow-green flowers open in March and are wind-pollinated. They have either four minute anthers or a hidden ovary. The latter develops, after fertilisation, into a white berry. These berries are palatable to mistle thrushes and other birds. The seeds are sticky and tend to stick to the beaks of the birds that eat them. In attempting to dislodge the seeds the birds often rub them off on to tree bark and into crevices. The germinating seed produces roots which invade the tree for nourishment and develops into a green shoot which divides repeatedly until the plant becomes a ‘bush’ which can be 2.0m across (2).
Oliver Rackham (3) states that, “Mistletoe ... is usually seen on exotic trees – cultivated apple, hybrid lime and hybrid poplar – with a preference for old specimens” and that, “it has a natural habitat on ancient native trees, especially hawthorns”. He also tells us that, “it very rarely occurs in woods, ancient or recent” and that, “It is very rare on oak”. In another passage he states that it is, “A specifically savanna plant” and that the presence of its pollen in the pollen record tends to indicate a warm period in which the savanna habitat (open grassland with scattered trees) was dominant. He goes on to describe Hatfield Forest, in Essex, which, “is its (i.e. Mistletoe’s) chief stronghold on wild trees, it occurs on old hawthorns and old maples, but only in the plains, and not in the woods.”
I have seen Mistletoe growing on an old, isolated hawthorn on Barnack Hills and Holes National Nature Reserve in Cambridgeshire – little did I realise, at the time that I was being afforded a glimpse of an ancient savanna!
In Britain Mistletoe is found in England and Wales, northwards to Yorkshire. It is mostly local in its occurrences but it is especially common in those southern parts of the English/Welsh borders either side of the Severn Estuary (4). I have seen apple orchards in Herefordshire where every other tree seemed to bear a heavy burden of Mistletoe.
Just before Christmas 2008 I was on the top-deck of the number 23 bus, returning to Chorlton from Stockport. All around me noise was blasting out from digital ‘post-music noise’ generators which were competing with the loud, one-sided conversations that people were holding on their mobile phones. On the outskirts of Didsbury village I involuntarily added to the cacophony by emitting a small squeak of surprise (I think I got away with it!). The cause of my minor outburst was a glimpse of the distinctive ‘starburst’ shape of a Mistletoe plant in a lime tree. Until that moment I had assumed that we had no Mistletoe in South Manchester. When, a few days later, I mentioned this sighting to Alison Hunt, of West Didsbury Residents’ Association, she said that she had also seen it in West Didsbury and directed me to another two lime trees hosting Mistletoe plants (5). Subsequently I learned, from members of Manchester Field Club, that there used to be a Mistletoe plant on an old apple tree in Fletcher Moss Gardens (6). The tree was cut down a few years ago – but perhaps it was the original source of the lime tree infestations observed by Alison and me?
In his great cultural flora, ‘Flora Britannica’, Richard Mabey (7) tells us that Mistletoe was, “one of the most revered plants of early herbalists” and it was credited with extraordinary powers, both curative and magical. It was also, and occasionally still is, the focus of much folklore and many customs – particularly in those regions where it is common. Some of this lore may be very old but Mabey urges caution over linking Mistletoe with ancient druidic practices. Briefly, the druids were supposed to have used golden sickles to harvest Mistletoe from oak trees and to have used it in their sacred rituals. It appears that much of this story was invented in the 18th century by an eccentric, antiquarian cleric, called William Stukeley, who read far too much into some vague hints in a book by the Roman author, Pliny.
Mistletoe has also been associated with fertility and this is probably why people still kiss under it at Christmas time. I’ll leave you with a verse from a favourite poem entitled ‘Christmass’ from John Clare’s, ‘The Shepherd’s Calendar’ (published 1827) (8):

The shepherd now no more afraid
Since custom doth the chance bestow
Starts up to kiss the giggling maid
Beneath the branch of mizzletoe
That neath each cottage beam is seen
Wi pearl-like-berrys shining gay
The shadow still of what hath been
Which fashion yearly fades away

Dave Bishop, January 2009


1. Wikipedia article on Mistletoe and Relatives: http://en.wikipedia.org/wiki/Mistletoe

2. ‘Book of the British Countryside’, Drive Publications, 1973

3. ‘Woodlands’ by Oliver Rackham, Collins, 2006

4. ‘Interactive Flora of the British Isles’ (DVD ROM) by C.A. Stace, eds R. van der Meijden & I. de Kort, ETI bioinformatics, 2004

5. Personal Communication from A. Hunt (West Didsbury Residents’ Association), December 2008

6. Personal Communication from A. Locksley, P. Tolfree and A. Hill (Manchester Field Club), January 2009

7. ‘Flora Britannica’ by Richard Mabey, Sinclair-Stevenson, 1996

8. ‘The Shepherd’s Calendar’ by John Clare, eds. Eric Robinson & Geoffrey Summerfield, Oxford, 196?

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