it's beautiful, but what is it?

[urban_greenwatch]

All along the tow-path at the moment are swathes of a beautiful blue flower, that grows in long, knotted stems on tough dark green stems with thin, afterthoughtish leaves. I've collected its seeds for a few years now (for wildflowers) but I still don't know its name. Time to find out!

It's a blue flower, so obviously my starting point is a Cornflower, the famous blue face of unweedkillered cornfields. I'm pretty sure it's not a Cornflower (soil wrong, stem wrong, flower the wrong shape) but shock! the third suggestion on google image is clearly the right flower. Number five of Holly Golightly's top 10 something blues is the right flower, and identified as a cornflower. The story of Queen Louise of Prussia keeping her kids entertained and quiet by weaving wreaths of cornflowers, too, that would work better with this flower than with regular cornflowers, it makes itself into wreaths. Perhaps it is a cornflower after all, just a different sort.

Time to get serious about identification. By serious, of course, I mean searching British Wildflower's index page for the word "blue". And, almost immediately, I have a contender; the gorgeous Sow Thistle Common Blue. Alas, though the flowers are right, the stem is wrongly arranged, the leaves all wrong, and anyway, it's not common. My boistrous riverside scrambler is something else. Nothing similar in Floral Images's blue gallery, either. Is it an escaped exotic? Perhaps someone a bit more local might help? Someone selling waterside seed mixes sourced from the thames?

Damn, I've checked through the unfamiliar names, but to no avail. My best match is Hairless Blue Sow Thistle, but given as how it's blue, slightly hairy and more knapweed-like in appearance than sowthistlesque I must retreat defeated. For now!

Thanks to j4 this is identified as chicory, famous for pretending to be coffee and curing intestinal worms. It's also a famous Roman herb: "Chicory is an ingredient in typical Roman recipes, generally fried with garlic and red pepper, with its bitter and spicy taste, often together with meat or potatoes." More culinary uses here.