This is a tale of two corydalis. One spreads steadily, but very slowly, the other is worrying the invasive plants people.
Corydalis solida ‘Blushing Girl’ (above) is a spring ephemeral for woodland conditions, at its peak today. It comes and goes relatively quickly in spring, then its little tubers sit and wait to do it all again the following year. The soft pink of its crowded flower heads is lovely, but it spreads only slowly.
Corydalis solida has a wide European distribution and this form originates from the great Latvian plantsman Janis Ruskans. It was available in the US from the late lamented Seneca Hill Nursery but no one, not even Odyssey Bulbs who list a huge range, seems to list it. In the UK, there are three stockists.
Since I’ve started feeding my clump with Miracle-Gro it’s spreading; I split it last year and it’s increasing noticeably. However, no seedlings. This is because individual clones of Corydalis solida are self incompatible – they will not set seed when fertilized with their own pollen. I’ve been tempted to buy one or two different ones, so they’ll cross and I’ll get seedlings. Now I wish I had, but I'd been trying to be sure that the lovely ‘Blushing Girl’ stayed true.
By contrast, there’s Corydalis incisa. This is an annual or biennial from Japan, Korea, Taiwan and China described as “startling” by the authors of the excellent book Bleeding, Hearts, Corydalis and Their Relatives (Available in Britain from amazon.co.uk and available in North America from amazon.com). They also say that they’ve seen it naturalized along the Bronx River in New York City.
As you’ll have guessed, no incompatability problems here and it now seems to be spreading in the City sufficiently to have alerted The New York Botanical Garden. It’s also been spotted elsewhere on the east coast: Maryland, DC, and Virginia.
This is not a plant that’s widely grown in gardens, it’s stocked by four UK nurseries and by Sunshine Farm & Gardens in the US so, I have to say, it’s entirely possible that it escaped from one of the City’s botanical gardens!
But let’s not get carried away. Of course, we don't want another plant smothering our natives along river banks and in flood plains. But it It’s only been seen as an escape for a few years – which, in ecological time, is just a moment– and, as we know, sometimes plants that seem threatening just fade away. In the meantime, enjoy ‘Blushing Girl’ and the many other forms of Corydalis solida. I’m going to keep pouring on the Miracle-Gro and take a closer look at those listed by Odyssey Bulbs.