Wildlife on Walls: 7. Wall Pennywort

Wall pennywort Umbilicus rupestris is one of those plants that would be much less common if humans hadn't built the perfect habitat for it, althought its distribution is geographically restricted by climate. It's confined mostly to the milder south western part of the British Isles. This photograph was taken near the Pembrokeshire village of Dale in Milford Haven, where the distinctive style of dry stone walling, constructed from vertical flat rock, provides the perfect niche for the plant.


I have tried to introduce this plant in a stone wall in  my garden here in north east England and although it survived for a while our severe winters killed it. 


The leaf stalk is attached to the centre of the fleshy, circular leaves, like an umbrella shaft - an arrangement known as peltate in botanical parlance. That produces a belly button-like dimple in the upper leaf surface, which accounts for its other common name, navelwort. John Gerard also included the mildly erotic names lady's navel and hortus veneris (the garden of Venus) in his herbal.

The Beguiling Beauty of the Scorpioidal Cyme

Botanical descriptive terminology provides a rich source of interest for anyone who enjoys the sounds of words and their precise economy of meaning. Try speaking the following, a few times over, as an incantation: panicle; raceme; dichasium; corymb; cyme; umbel. They are all terms found in identification keys and floras for the arrangement of flowers in an inflorescence, combining precision of meaning with a hint of the classical linguistic roots that underpin botany, that most ancient of biological sciences.


The plant in the image below, comfrey, has an inflorescence described by my favourite of these terms: a scorpioidal cyme. 


A cyme is, according to the glossary in my old college copy of Clapham, Tutin and Warburg's Flora of the British Isles, 'an inflorescence whose growing points are each in turn terminated by a flower, so that the continued growth of the inflorescence depends on the production of new lateral growing points'. In comfrey's case, and in the case of many members of the family Boraginaceae, to which it belongs, the cyme is curled like a scorpion's tail, with a degree of precision that could surely be expressed in a mathematical equation. If you have forget-me-nots in your garden, they too are members of the Boraginaceae and have flowers arranged in a scorpioidal cyme.

The inflorescences, with their diadems of purple buds that have a sting in their terminology, must surely - at some time - have inspired a jeweller to create something similar as a brooch.....?


Incidentally, the publication of Clapham, Tutin and Warburg's Flora of the British Isles, a landmark in British field botany, also celebrates its diamond jubilee this year.