categoryZEvergreen Evergreen List 

MISTLETOE

Viscum album

Bastard-toadflax Family [Santalaceae]

Flowers:
month8feb month8mar month8march month8apr month8april

Berries: berryZpossible        berryZwhite  (poisonous, sticky)
berry8Nov berry8Dec

category
category8Evergreen
status
statusZnative
flower
flower8green
morph
morph8actino
petals
petalsZ4
stem
stem8round
toxicity
toxicityZmedium
sex
sexZdioecious

26th April 2013, Linchmere, nr Haslemere, West Sussex Photo: © Dawn Nelson
On a Poplar Tree host. Not un-like the tree gall Witch's Broom.


26th April 2013, Linchmere, nr Haslemere, West Sussex Photo: © Dawn Nelson
On a Poplar Tree host. Roughly spherical populations up to a metre across and usually at un-reachable heights.


23rd Feb 2016, a tree, Leigh, Lancs. Photo: © RWD
Usually in the shape of a globular cluster with stray braches sticking out around the edges.


20th April 2013, nr. Bletchworth, Surrey. Photo: © Dawn Nelson
Usually so high up in the tree as to be un-reachable except for the long pole used to harvest it for Christmas Yuletide and the kissing underneath thereupon. A branched mass up to a metre across.


20th April 2013, nr. Bletchworth, Surrey. Photo: © Dawn Nelson
Leaves yellowish-green, elliptical and leathery. Usually in pairs.


23rd Feb 2016, a tree, Leigh, Lancs. Photo: © RWD
 At branch junctions are several flowers, two, three or as here in the centre four. Because the plant is dioecious, and the male and female flowers are on separate plants, with this specimen having berries, these must be female flowers.


23rd Feb 2016, a tree, Leigh, Lancs. Photo: © RWD
Berries small, pearly-white, spherical. Highly poisonous! There are four in this photo...


23rd Feb 2016, a tree, Leigh, Lancs. Photo: © RWD
 A very architectural plant: short and dead-straight branches in opposite pairs or in triplets at a characteristic forward angle, branched fractally to end branches which have a pair of opposite leaves shaped rather like aeroplane propellors but often curved slightly forwards.


20th April 2013, nr. Bletchworth, Surrey. Photo: © Dawn Nelson
 It is dioecious, having male and female flowers on separate plants. These are female flowers. They are very stubby, with short yellowish-green petals and slightly reminiscent of a pigs snout and ears. Here situated at a Y-branching of the stem.


20th April 2013, nr. Bletchworth, Surrey. Photo: © Dawn Nelson
 Female flowers.


20th April 2013, nr. Bletchworth, Surrey. Photo: © Dawn Nelson
 Three female flowers. In the centre of each flower is the circular nectary which surrounds the central single stigma.


Some similarities to : Witches' Broom which is a gall on Birch or Hornbeam and also on Wild Cherry (Gean) trees trees usually caused by the fungus Taphrina betulina which look rather like bird's nests, but they are usually more dense than is Mistletoe.

Uniquely identifiable characteristics

Distinguishing Feature :

Mistletoe is dioecious, with male and female flowers on separate plants, the sticky white berries only appearing (between November to December) on female plants. The berries are eaten by Mistle Thrush birds as well as by other birds, but they are so sticky that they also stick to the bird's beak as they try to eat them from where they are ready to be implanted on the next high branch of a tree that the bird visits. Because birds prefer to be high up in the trees, Mistletoes is to be mostly found near the top of the tree. But Mistletoe will only take on first or second year tree growth, and even then can take a whole year to 'root' and establish a connection with the host tree before it can obtain nutrients and fluids. Before that first year is up, it is on its own.

Mistletoe is  Hemi-parasitic and grows on, obtaining some nutrients from, deciduous trees, especially Malus (Apple), Populus (especially Black Poplar), Tilia (Lime) and Crataegus (Cockspurthorn & Hawthorn). Only rarely ever on Quercus (Oak). It is grown commercially on mainly Apple Trees in orchards for the Christmas trade in mistletoe for kissing under. It is capable of photosynthesis itself but draws water and minerals from its host vascular system at distinct swellings or gall where the two conjoin.

Out of several sub-species found in the World, only the 'parent' grows in the UK, Viscum album. It contains a toxic protein and lectin called Viscumin which has a high molecular weight. Other sources make mention of viscotoxin as one of the toxins. They are, like Ricin, a RIP, a Ribosome Inactivating plant Protein which is another poisonous lectin, although the two target and bind to differing sites. Although Mistletoe is poisonous, fatalities are rare. It is concentrated in the white berries but is said to be present in the whole plant.

Mistletoe does, of course, contain other chemical compounds, but because Mistletoes can grow on a wide variety of differing trees and is hemi-parasitic on them, obtaining some nutrients from them, the composition and proportions of these secondary metabolites can vary. However, any toxicity of these compounds will probably pale into insignificance compared to the toxicity of the viscotoxins. A new acyclic monoterpene diglycoside has been found in Mistletoe, but it lacks a common name and the chemical name is very long.

Its greatest population density in the UK is in Somerset and Devon with a very broad spread around the home counties and a smaller outbreak on the Mid-Wales border. Virtually no presence north of South Yorkshire apart from one or two hectads.


  Viscum album  ⇐ Global Aspect ⇒ Santalaceae  

Distribution
 family8Bastard-toadflax family8Santalaceae

 BSBI maps
genus8Viscum
Viscum
(Mistletoe)

MISTLETOE

Viscum album

Bastard-toadflax Family [Santalaceae]