Pignut (Hognut)

“I prithee, let me bring thee where crabs grow; and I with my long nails will dig thee pignuts.”

- The Tempest, William Shakespeare

Pignut, also known as hognut, kippernut, cipernut, arnut, jarnut, hawknut, earth chestnut, groundnut and earthnut, is a small perennial herb that once grew in ancient grasslands and fields across Britain, Europe and parts of North Africa. Due to a loss of habitat, they are most commonly found at the edges of fields and in woodlands these days, but if you’re lucky enough to encounter a whole field then take sparingly with as little damage as possible as the harvesting process can be quite intensive.

The ‘nut’, which is in fact a type of starchy tuber or root, resembles a chestnut in colour and size but has a sweet, delicately aromatic flavour comparable to hazelnut or almond. Raw, they have the texture of pickled garlic, adding a pleasurable crunch to meals, and sometimes come with a slightly spicy aftertaste like a mild radish.

Foraging Pignuts

Identification

Pignuts are a member of the carrot family, apiaceae, with leaves that bear a resemblance to carrots in structure. Whilst this may seem like a harmless piece of information, it is important to give plants from this family due respect as some are highly poisonous, most notably Hemlock and Hemlock Water-Dropwort. The main difference between Pignut and it’s poisonous cousins is size; pignuts are considerably smaller, growing between 1-3ft (30-90cm). By contrast, Hemlock grows 5-8ft (1.5-2.5m) and Dropwort up to 6ft tall (1.9m).

Above is a photo of the entire plant, harvested from flower to root in mid June.

Harvesting

First thing first, these little flowers will make you work for their tasty root. We bent two trowels before swapping to a reinforced tree planting spade. If you’ve ever tried removing Bindweed from a garden then you’ve come across a similarly fragile root to Pignuts. The nut is usually between 3 - 6 inches (10-20cm) below ground, so dig close to the plant’s base and lift a small chunk of soil up. This is made much harder thanks to the established root systems of the neighbouring grasses found in the habitats where Pignuts are common. Once lifted, you’ll have to get your hands in the soil and loosen it up. Keep an eye out for the chestnut coloured root that’s a similar size and shape to popcorn.

Once located and harvested, plug the removed soil back up and take your collection to a nearby stream or bucket of water and rub the soil and chestnut coloured skin off them. Beneath the skin, the pignuts look even more like popcorn! Store them in a cool, dark place until you’re ready to cook with them or eat them right away (raw).

Alternatively, if you’re foraging them in a woodland, you can use a pointed stick to follow the stem of the plant below ground, but this too is fiddly and time consuming, so prepare for an hour or so of solid harvesting if you’re after a few.

Another thing to bear in mind is that the plant likes to first grow parallel to the surface of the ground before taking a right angle to aim for light. This usually doesn’t last more than 1 inch or 2cm, but keep this in mind if digging as you won’t want to dig too close to the base of the plant and end up chopping it off and losing your prize.

Cultivation

Something we plan to do this year is try to cultivate our own Pignuts. We already had one growing in a raised bed that had self seeded and popped up. If you decide you enjoy the flavour of this plant but don’t want to work as hard for them then here are our plans for cultivating our own crop (and we invite you to try too).

Firstly, collect the seeds from wild Pignuts you’ve encountered before harvesting the root. Around this time of year until later in the summer the flowers are turning to seed. Once harvested, keep the seeds in a cool, dark place and sow them in the following spring in non-alkaline soil with plenty of drainage. We’ve heard that the seeds are quick to germinate, so as soon as they’re large enough to handle, prick out the seedlings into individual pots or directly into a veg patch and see what happens! Research on the subject implies that the species responds well to cultivation and can actually increase the size of the roots for harvest.

I’ll keep you posted on how it goes.

Food Applications

So now you have them, what can you do with them?

As I mentioned, eating them raw is the most common forager’s response, and as nice as they are, I’m always of the mind to experiment. So I’ve taken a small crop of Pignuts into my kitchen for some culinary experimentation. As of yet I don’t have any results to show you because a lot of what I’m attempting takes time to age or ferment. But I’ll talk you through my thinking and projects with no promise of success and if anything catches your eye then feel free to have a go too and let me know how it works.

Firstly, dehydration. The photo above is of the cross section of a toasted Pignut which spent 30 minutes at 180C / 356F. I wanted to see how the starches and aromatics would respond to temperature during the cooking process and it wasn’t a disappointment. With a light smell of marzipan, the Pignut became sweeter, harder and lighter (and lost 1/8th volume through evaporation). This has given me the idea to test a far longer dehydration in the future to preserve them and perhaps turn them into a light almondy smelling nutmeg type ingredient (designed to be grated over savoury or sweet alike).

The next idea I’ve had is a standard lacto-ferment. Thanks to the clearly high sugar content of the root, I’m subjecting it to the same conditions as garlic during a brine solution ferment. I have no idea which flavours will be accessed or how, but fermentation rarely disappoints. I plan to ferment them at an ambient temperature in a dark corner for 3 weeks, burping the jar each day, before sampling and testing the pH. From there, I may continue to ferment them for another month to see where else the flavour transforms to. Will update accordingly.

My next adventure is to attempt to ‘blacken’ them. As this type of fermentation works for garlic, once again I’m trying to follow suit with Pignuts. This process will take a minimum of 2 weeks before I can update this post with the results, but I’m intrigued to see what happens.

In the meantime, enjoy your Pignuts raw, grated, or chopped and fried along with anything else from the garden. I’d imagine they’re very tasty roasted for 40 minutes as mentioned before, then spiced and salted for a great movie night snack.

Whatever you get up to with your Pignuts, I hope you’ve enjoyed this blog post. Keep an eye out on our Instagram for updates as and when they happen; I’ll post both successes as well as failures for all of the above projects. But for now, happy foraging and stay safe.

- Sam, the chef