Saturday, March 20, 2010

Lady's Smock Cardamine pratensis

I am an amateur naturalist trying to learn something about everything living in my garden.

Photo 1 shows an attractive flower I found growing wild in a neglected corner of my garden early last summer.

A little time spent with my trusty copy of The Wildflower Key (Francis Rose) and I'm fairly confident my plant is Lady's Smock. The leaves of my plant are also rather characteristic (photo 2) with the lower leaves tending towards round with the largest leaf being the one furthest from the stem, whilst the upper leaves are rather long and narrow.

My copy of The Englishman's Flora (Geoffrey Grigson) lists around thirty alternative common names for Lady's Smock from the pretty Cuckoo Bread, Cuckoo flower, Lucy Locket and Milking Maids to the less flattering Pig's Eyes and Bog Spink!

The scientific name for my flower is Cardamine pratensis. Pratensis is from the Latin 'of meadows'. From some web searching I understand Cardamine owes its heritage to the anicent Greek physician Dioscorides (ca. 50AD) who used the name for some cress-like plants, karda being Greek for 'heart', and damao to 'tame or overpower'. (I've read that Lady's Smock is an edible, spicy, salad leaf, though I can't vouch for the truth of this.)

Lady's Smock is a favoured food of the caterpillars of the Orange Tip butterfly.

C. pratensis is a perennial, native to the British Isles and is highly variable. The paper here gives a flavour of the lengths the professionals have gone to in attempting to characterise it. My copy of New Flora of the British Isles (Stace) sums things up rather bluntly however as "impossible to subdivide usefully; identity of [named] variants [...] is very dubious". My attempt to get some basic amateur understanding of the issue led me into a study of polyploidy. I'm certainly no expert on genetics but briefly my understanding is this:

As most people know, at times the DNA inside living cells gets packaged into structural units, the chromosomes. A microscope reveals we have 46 chromosomes. Closer investigation reveals that these 46 are in fact present as two largely similar sets of 23 i.e. 23 chromosomes from our mother and a similar 23 from our father. (The phrase 'largely similar' skips over a wealth of detail, such as the fact that a certain chromosome from our mother might carry a different characteristic, say eye colour, to that from our father etc. - but never mind that here) . For humans we say "2n=46". Other mammals have other chromosome counts, for example I read variously on the web that the kangaroo has a mere 2n=12 whilst the European hedgehog boasts 2n=88 (in general there is no link between chromosome number and the size or complexity of a creature).

In the case of many plants, a lesser number of insects, amphibians, fish and a very few mammals (one being an Argentinian Plains Rat - see the parade of polyploids here!) however, things are more complicated. Some varieties of strawberry for example contain not, as we humans, two largely similar sets of 23 chromosomes but no fewer than eight sets of seven chromosomes. This gets written as "8x=56". This condition of having more than two sets of chromosomes is termed polyploidy.

The fact that more than 30% of plants go in for polyploidy would seem to indicate it must have some important benefits. There are many theories as to what these benfits might be. It's been suggested for example, that polyploidy may promote greater variation in a species and thereby help it evolve ('radiate') more easily into new environments, or that polyploidy may provide protection against 'in-breeding' issues that might otherwise arise for plants that self-fertilise. It seems also that some polyploids are healthier and more vigorous than non-polyploids. In all however, there seems to be no universally accepted theory of why so many plants are polyploids. Another of nature's mysteries!

Anyway, all of this preamble basically allows me to comment that my garden weed occurs in a bewildering variety of genetic 'forms' from the 'diploid' 2n(=2x)=16 through types with chromosomes numbers of 14, 15, 16, 19, 20, 21 – 28, 30, 32, 37, 42, 44, 45 and 48.

After the science, who better to have the last word than the Bard. From the song 'Spring' at the end of Love's Labour's Lost:
When daisies pied and violets blue,
And lady-smocks all silver white,

And cuckoo-buds of yellow hue
Do paint the meadows with delight,


Anonymous said...

What a thoroughly brilliant blog.

Keep it up! I heard recently (on QI - so it must be true)...that the most likely place, on the planet, to find 'new species' in your own back garden! That's how diverse and abundat life is on, keep up th good work...and if you can't find something in your just never know!


An inspiration!

Richard Carter, FCD said...

Here's a photo I took of an orange-tip butterfly on some lady's smock.

sebi_2569 said...

nice photo; nice blog; bravo