Viola tricolor, Darwin and ecology

This tiny, beautiful little plant appears each year in unexpected places in our garden, germinating from seed scattered from who knows where. It is also known as heartsease, a lovely name perhaps due to its pleasant perfume, or maybe to the arrangement of petals, described by William Turner in 1848 as  ‘Two faces in a hoode’, which led to the flower being seen as a symbol of love.

In French the name for any flower in this family is pensée (from which comes the English pansy), meaning thought, since it is an emblem of  remembering.   This enables me to make a connection to a giant of nineteenth-century thought.  I wanted to start with this plant because of its link to the name I’ve chosen for this blog and to Charles Darwin.  In The origin of species Darwin writes:

I have, also, reason to believe that humble-bees are indispensable to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower….Hence I have very little doubt, that if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare or wholly disappear.  The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests….Now the number of mice is largely dependent, as everyone knows, on the number of cats….Hence it is quite credible that the presence of a feline animal in large numbers might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!

He goes on just a few lines later to say:

In some cases it can be shown that widely-different checks act on the same species in different districts.  When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this!

Darwin’s great work was published in 1859, before the word ‘ecology’ even existed: it was coined in 1866 by one of Darwin’s greatest fans, the dashing German biologist Ernst Haeckel. Clearly, however, Darwin’s vast knowledge as a naturalist gave him an awareness of the interdependence of all living things, plants and animals, and of their environments.  There’s an interesting series of radio programmes on Darwin, originally broadcast to celebrate his bicentenary in 2009, available for listening here for anyone who wants an alternative to reading his magnum opus.

Note: From noise to aeronautics: for more on how Darwin’s term  ’humblebee’ was replaced by today’s word ‘bumblebee’  see here.