At the very least I would suggest taking some care about introducing lesser celandine (Ficaria verna) to your garden. Its early growth, glossy leaves, cheery yellow flowers and edible uses all make it attractive, but it has a well-deserved reputation for being invasive in damp or shady areas. In North America, where it is introduced and where several states list it as a noxious invasive species, the cons almost certainly outweigh the pros. In Europe and North Africa, where it is either native or a long established introduction, the situation is different.
As its Latin name suggests, F. verna is a plant of the spring. It emerges early, flowers early and dies away again before some other plants have even got out of bed – a classic pattern for woodland floor species adapted to making use of spring sunshine before the trees leaf out and hog the lot. Most plants that do this are bulbs – think wild garlic, snowdrops and wild hyacinths (bluebells) – and indeed it might be fair to include lesser celandine in the spring bulbs despite its place in the buttercup family, due to the fleshy little tubers that are the key to both its bulb-like lifestyle and its invasiveness.
Incidentally, the shape of these tubers explains lesser celandine’s other common name: pilewort. Their shape was considered to resemble that of haemorrhoids or piles. Under the ancient ‘doctrine of signatures’, God was held to have marked each species to indicate its use to humans, so this resemblance was considered a sure fire sign that celandine would cure piles.
In truth, the doctrine of signatures should probably be placed in the same location as haemorrhoid cream, but there is no denying the tubers’ use to the plant itself. A handy underground store of nutrients, chock full of toxins, is just the thing needed for an early start to the year. It is also the key to the plant’s persistence, as it is hard to remove all the tubers, and the ease with which it can be accidentally spread around the garden (or the wild). As a result, lesser celandine quickly forms a carpet of growth in favourable conditions.
All this said, there are also reasons why lesser celandine finds it difficult to become a serious pest in any well-managed garden. Despite the seeming ability of the tubers to get everywhere, it doesn’t actually ‘run’, either underground like couch grass or overground like its cousin, creeping buttercup. It’s also a very low growing plant. Its ambition is not to get into the full sun, so it rarely provides serious competition for other plants and it is really quite easy to weed out. It also has an Achilles’ heel, which is that it needs constant moisture to stop the tubers drying out, and it’s never going to be a problem in dry, sunny areas of the garden.
I now let lesser celandine grow in some areas of my garden, where it fills a useful niche as an early spring green – although some caution is required here too! All parts of the plant contain a toxin called protoanemonin, common to the buttercup family. You’ll know if you get protoanemonin in your mouth as it creates an unpleasant burning sensation in the mouth and throat. Fortunately, protoanemonin is easily broken down by heat or drying so it is easy to get rid of.
Different sources seem to have different ideas about the amount of protoanemonin in lesser celandine. Miles Irving, the author of ‘The Forager Handbook’ says “Leaves contain protoanemonin, but in minute quantities. Levels are said to increase as the plant comes into flower, but I have eaten plenty of leaves from flowering plants and come to no harm.” and “Leaves are attractive; the flavour quite mild; good bulking for wild salads containing other, stronger flavours.” Perhaps English celandine is different from Scottish, or perhaps Miles is just more tolerant than I am, but I can’t say that this matches my experience. I only use lesser celandine greens cooked, as a pot herb, an ingredient in leaf sauce, in a stir fry (where they keep their succulent texture) or fried in olive oil until they become crispy. Plants for a Future have an interesting note that the flower buds make a good substitute for capers, but I have yet to try this. Whether or not levels of protoanemonin increase with time, I make most use of it early in the season when there are fewer other leaves around. Miles also says that the tubers have a flavour and texture similar to potatoes and can be use boiled or roasted, but my opinion is that life is too short.
Some variations on the regular lesser celandine are available. There is are varieties that do not produce tubers and are therefore much easier to control. I’m not sure, however, how easy this strain is to get hold of and whether or not it will tend to revert to tuberising as it self-seeds – I suspect so. There is also a handsome bronze variety which looks very striking with the bright yellow flowers against dark purple leaves.