Monday, 23 October 2017

Pellitory of the Wall

What is the difference between Pellitory of the Wall and the Daily Mail?  Clearly one is a noxious and pernicious growth whose existence is difficult to justify and is best avoided; by contrast Pellitory of the Wall, Parietaria judaica, is an interesting species of plant to which we should accord more respect. The first is passed by many of us on our daily walks and rarely noticed and sadly I am one of those who fall into this category. Come to think of it the second subject is, in a sense, also passed daily - if our bowels are in good working order.
Pellitory of the Wall is a member of the Nettle Family, Urticaceae,  but despite its relationships the plant does not sting.  Over the decades it has also been referred to as Parietaria diffusa and P. ramiflora. Its common name is very appropriate for it is rarely seen in any location other than on, or at the base of, a wall, the only exceptions I can recall being the occasional plant growing on rough, stony ground.
Pellitory of the Wall clinging to the wall - where else? - of Holy Cross
Church, Byfield. 18 October, 2017
Certainly John Clare knew it from this distinctive habitat for in his 1821 work, The Village Minstrel, he described a location as being 'Where the mouldering walls are hung with Pellitory green'.
Gill Gent and Rob Wilson, point out that it often occurs on the brickwork of canal lock-gates. [Gent and Wilson, Ref 1] Beyond Britain I have often noted it on ancient buildings and archaeological sites in southern and western Europe.
Despite its superficially mundane nature it has a number of interesting features. For example, some of the stigmas on this wind-pollinated plant are red whilst the others are white. Why? There is no apparent reason. To avoid self-fertilisation these stigmas shrivel up and cease to function once pollinated and it is only then that the associated anthers release their pollen. Like stinging nettles, the pollen is released by an almost explosive mechanism whereby the stamens spring outwards, discharging a cloud of pollen, allowing it to drift away in the breeze. Being reliant on wind rather than insects it can be found in flower throughout the winter months, but visually it must be admitted that these flowers are excessively dull.
It clings to other walls in the village too. Byfield, Northants.
18 October, 2017
The Red Admiral Butterfly. Vanessa atalanta, generally uses the Perennial Stinging Nettle, Urtica dioica and the Small Stinging Nettle, Urtica urens, as food plants for its caterpillars but will on occasion also use Pellitory of the Wall. 
Pellitory of the Wall. The clusters of inconspicuous flowers are wind
pollinated. Byfield. 18 Octpober, 2017

As for humans, it was once frequently used by herbalists, being 'a most efficacious remedy in stone, gravel, dropsy and suppression of urine.' [Wren, Ref 2] The poet and playwright, Ben Jonson wrote:
                                  ' A good old woman...did cure me
                                   With sodden ale and pellitorie o' the wall'.
                                                                                         The Alchemist, III

So, this humble plant, much esteemed in the past, has an interesting history. Indeed, its habitat may in part relate to its cultivation by monks or nuns in physic gardens and subsequent escape, to initially colonise the walls of priories and abbeys.

Tony White:


1.  Gent, G and Wilson, R  2012  The Flora of Northamptonshire and the Soke of  Peterborough  Robert Wilson Designs/B.B.S.I

2. Wren, R.C. 3rd edition 1932  Potter's Cyclopaedia of Botanical Drugs and Preparations
Potter & Clarke, Ltd.

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