This cuckoo pint aka wild arum aka lords and ladies aka Arum maculatum - and scores of other names - has been growing in our compost heap. Digging it up to transplant it into the garden revealed its underground tuber.
Cuckoo pint's rapid growth in spring is fuelled by the starch stored in its tuber, and in 16th. century Elizabethan England this was used to starch, and so stiffen, the ruffs that royal courtiers wore around their necks. John Gerard, in his Herbal or 1597, wrote a description of the perils of starch extraction from this poisonous plant:
"The most pure and white starch is made of the roots of Cuckow-pint; but most hurtful to the hands of the Laundresses that hath the handling of it, for it choppeth, blistereth, and maketh hands rough and ragged and withall smarting".
Some examples of elaborate ruffs, that would have been supported with a wire frame as well as with starch:
Public domain image source: http://en.wikipedia.org/wiki/Elizabeth_I_of_England#/media/File:Elizabeth_I_(Armada_Portrait).jpg
Public domain image source: http://en.wikipedia.org/wiki/Ruff_%28clothing%29#/media/File:Anna_Rosina_Marquart.jpg
Public domain image source: http://en.wikipedia.org/wiki/Elizabeth_I_of_England#/media/File:Darnley_stage_3.jpg
For more spectacular examples and a history of the Tudor ruff, click here
It's surprising, given the poisons that are present in cuckoo pint, that its starch was also used as a food known as Portland sago. Here's a description from C. Pierpoint Johnson's The Useful Plants of Great Britain: a Treatise,of 1863:
'The root is thick and tuberous; while fresh, it is extremely acrid and poisonous, but its injurious qualities are capable of being destroyed by heat, so that when well baked it becomes edible, and, consisting principally of starch, is nutritious. In the Isle of Portland the roots of the Arum are collected and eaten by the peasantry, and some years ago a kind of farina was prepared from them, and sold as Portland sago or Portland arrow-root, but little is now made. In Switzerland the fresh roots are used as a substitute for soap. The juice is a purgative, but far too violently so to use used as a physic.'
Needless to say, cuckoo pint should never be eaten, cooked or uncooked' those Portland islanders were probably poisoning themselves in ways that medical science at the time would not have been able to diagnose.