Is it borage? Is it forget-me-not? No, it's green alkanet! Photograph: Jane Perrone.

Editor’s note: This post was first written in 2016 but was last updated in April 2024.

If you're a member of more or less any social media platform, you've probably seen a post in the past month that reads something like this:

"I've seen this plant in my garden/on my allotment/on a grass verge, can anyone tell me what it is/whether it's a weed?"

The comments below will go like this:

"It's borage."

"Forget-me-not, I think."

"No, it's green alkanet, it's a dye plant."

"Green alkanet, it's a horrendous weed."

"Borage. Or maybe comfrey."

"I think it's Brunnera."

"Forget-me-not."

"Can you eat it?"

The plant in question is almost always green alkanet (Pentaglottis sempervirens). You may not have heard of this plant as it’s not as well known as the plants it is often mistaken for: they are all members of the Boraginacae family, but different species.

Green alkanet does have piercing blue flowers not dissimilar to forget-me-nots, brunnera and borage, and hairy leaves that look a bit like comfrey, but once you get to know this plant it's easy to spot: the blue is sharper than a forgot-me-not - really, really bright, the leaves are too big for forget-me-nots and the flowers don't have the same star shape as borage.

You may have also heard that it is a dye plant. This is another red herring, sort of. It's another member of the borage family, dyer's alkanet (Alkanna tinctoria), that's used to produce a purple/red dye, although I understand a weaker dye can be obtained from green alkanet's roots.

Why is this plant appearing so often in social media? I think it's the blue flowers that do it: it really does stand out, even to people who are usually not looking closely at plants*.

This plant is not a native to the UK (few plants are, to be honest… more of that in another post!) It is indigenous to southwest Europe, and arrived in British gardens around 1700 : itwas first spotted as a naturalised (ie escaped) specimen in 1724.

What’s green alkanet good for, then? It's bemoaned as a weed by many: its deep, brittle tap root makes it tricky to eradicate completely, and doesn't really even serve as a wild edible - Plants for a Future gives it an edibility rating of one out of five, because although the flowers are edible, they don't add much other than a beautiful garnish.

Green alkanet taking over a front garden... what's not to like? Photograph: Jane Perrone.

So what is green alkanet good for? For some it's a weed - I let it grow around my pear tree but try not to let it spread about. It will grow where little else will, and the flowers are pretty and come in a long succession from spring to Autumn: if you hack it back to the ground it will return, unperturbed. Finally, and most importantly, the flowers are popular with pollinators, just like its tamer relative lungwort (Pulmonaria). They are also food for the larvae of the stunning day-flying moth the scarlet tiger (Callimorpha dominula).

If you do want to get rid of green alkanet from a space, you can dig it up, trying to get out as much of the tap root as possible. Put the plants in your green waste bin, or soaking in a bucket of water for a few weeks until the plant has rotted down, then add to the compost heap. As with other hairy members of the members of the Boraginacae family, wear gloves as the leaves can cause skin rashes.

*I think it's great that people can now use Facebook groups to expand their knowledge of plants, but I find some of the questions asked breathtaking In the knowledge gaps they expose - like the young woman who was weeding around the onions on her family allotment and wondered what the little red and white things she was digging up were - a glance at the picture showed radishes: and this is someone who is engaged enough with plants to be working on an allotment. Social media can be a real boon for beginner gardeners, particularly younger people who may not feel comfortable asking advice from the "old hands" on the plot. Mostly people commenting are doing their best, and are happy to help identify plants, but sometimes (often) they get it wrong: a lot of people confidently yet wrongly identify green alkanet as borage or forget-me-not. The "wisdom of the crowds" does eventually prevail, however, but it's certainly worth waiting until a dozen or more people have commented to see what consensus has been reached.

More by Jane Perrone