1. Slipper Limpet (Crepidula fornicata)
Invaded: Accidentally introduced in 1887 along with American Oysters.

The slipper limpet has invaded the European coast all the way to Spain, especially along the coasts of Brittany and Normandy. It feeds by filtering water and consuming a large quantity of plankton, thus chasing away mussels and oysters, which are also filtering mollusks, from their original environment.

Easy to find, the slipper limpet attaches itself at a shallow level, not more than 10 m deep. At low tide, they can be easily collected… Its meat is more tender than the limpet; it is delicate and requires only minimal cooking; it has a slightly nutty taste that should be brought out; its flavor is subtle and should not be masked; (from Worldwide Gourmet)

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2. American Bullfrog (Rana catesbeiana)
Invaded: increased in the late 1970’s, with the sale of tadpoles in small quantities as pets. Although there have been numerous escapees across the country a breeding population was not recorded until 1999.

Introduced as a pet in the 1970’s this voracious predator is a danger to much UK wildlife. (Introduced Species UK).

Large specimens have been known to catch and swallow small birds and young snakes; its usual diet includes insects, crayfish, other frogs, and minnows. Attempts to commercially harvest frogs’ legs have prompted many introductions of the American Bullfrog outside its natural range. (enature.com)

They can be barbecued, or fried, or sauteed. If you are going to harvest them yourself, then follow these guidelines:

Frogs are a breeze to clean. Rinse the frog, then grasp it behind the front legs with its head in your palm and place it belly down on a cutting board. Stretch the hind legs out and cut with a cleaver or heavy knife above the hip. Try to keep the legs attached as a pair to ease skinning and cooking. Work your finger under the skin between the frog’s legs. Then, pull the skin down the legs to the ankles, like peeling off a pair of tube socks. Cut off the feet and skin with a sharp knife and toss this tasty treat to the friendly barn cat keeping you company. Place the legs in a freezer bag with a tablespoon of salt per gallon bag of frog legs, fill the bag with water and refrigerate or freeze. This will avoid freezer burning the legs. The hip bones can be sharp, so double bag. (from The Missouri Conservationist)

So, does frog really taste “just like chicken”? Well, only if one of your chicken’s grandmothers was messing around with a fish – it has just a faint suggestion of fish flavor.. The flesh is mild and less stringy than chicken, more like Alligator actually. Frog cooks quite quickly, 20 to 30 minutes at a simmer depending on size. When it is done the legs will separate into separate joints and the meat will start to fall off the bones. (from Clove Garden)

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3. European Rabbit (Oryctolagus cuniculus)
Invaded: first introduced by the Romans, and then re-introduced by the Normans in the 12th century to provide meat and fur. (even better if you get it as roadkill)

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4. Ruddy Duck (Oxyura jamaicensis)
Invaded: Escaped from captivity in the 1940’s

“over-sexed and over here” (BBC News)

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Misc Animals – Chinese Mitten Crabs, Grey Squirrel, American Signal Crayfish, Zebra Mussels, and  many more non-human animals are covered in the Guardian article mentioned here.

I’m looking at the relationship between invasive species and their causes.
Taking a rather primitive approach, I want to offer up this solution: Eat Thy Enemy.
Many promise to be delicious–

1. Japanese Knotweed (Polygonum cuspidatum, Fallopia japonica)
Invaded: 1850’s. Imported from Japan as ornamental

“tastes like rhubarb, only better” – Steve Brill

Fantastic information on knotweed on Wildman Steve Brill‘s site.

Euell Gibbons’ “Stalking the Wild Asparagus” wrote that Japanese knotweed tasted like rhubarb and was good eats — apparently you could make pie, jam and even a tasty soup with it.
Back home, I peeled the bottoms of the foot-long stalks, removed its leaves, and sampled my polygonum notch-by-notch. Japanese knotweed is crisp and surprisingly tart raw, rather like an immature Granny Smith crossed with a tomatillo. Parboiled, the tips have asparagus-like first notes, followed quickly by a tart, high-in-Vitamin-C-punch — there’s a reason why it’s often compared to rhubarb.

Some recommend steaming it as a side dish or adding it raw to salads. I added it to tomatoes, cilantro, shallots, habanero pepper, and lime for a twist on salsa fresca. (from The Stoop, Ava Chin’s New York Times’ blog

Plants for a Future rates this plant rather well – although warns about photosensitivity from knoteweed’s oxalic acid content (same as rhubarb or sorrel).

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2. Pennywort (Hydrocotyle ranunculoides, Centella asiatica)* a.k.a. gotu kola
Invaded: 1980’s. Introduced commercially for use in garden ponds and aquaria

Stem, leaves and roots are edible. Used in salads, drinks, rice dishes, raita in Asia. Has health benefits attributed to it. (from Practically Edible)

Big glowing dissertation on its gustatory and salutory properties: Pennywort: The Elixir of Life

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3.Hottentot Fig (Carpobrotus edulis)
Invaded: 1886. Introduced from South Africa to stabilize soil and dunes

The creeping, smothering mats of Hottentot Fig out-compete native plants and reduce biodiversity by competing for nutrients, water, space and light. It is a plant of coastal habitats and as such threatens some of the most sensitive ecology in the UK.

On the upside, it has edible fruits, although sour can be made into jams. Not invasive (yet) in the north; mostly restricted to Devon/Cornwall area (NNSS)

Fruit – raw, cooked, dried for later use or made into pickles, chutney etc. There is very little flesh in the fruit and it must be fully ripe otherwise it is very astringent. Mucilaginous and sweetly acid. Leaves – raw or cooked. Succulent, they are eaten in salads and can also be used as a substitute for pickled cucumber. We find them too mucilaginous to be enjoyable. (Plants for a Future)

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4.  Common Water Hyacinth (Eichhornia crassipes)
origin: South America. Invasion date unknown

The plant is used as a carotene-rich table vegetable in Taiwan. Javanese sometimes cook and eat the green parts and inflorescence. (Duke, Handbook of Energy Crops) (also mentions that “eating the plant may induce itching,”  but perhaps only if raw?)

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5. Himalayan Balsam (Impatiens glandulifera) a.k.a. Jewelweed
Invasion: 1839. Western Himalayas.

Himalayan Balsam has been eaten in India for hundreds of years…the seeds are eaten, having a nutty flavour, while the young leaves are used as a vegetable.(from Eat Weeds UK)

Young leaves and shoots – cooked… Seed – raw. A delicious nutty flavour, but difficult to harvest in quantity mainly because of their exploding seed capsules which scatter the ripe seed at the slightest touch.  An edible oil is obtained from the seed.The plant is used in Bach flower remedies – the keywords for prescribing it are ‘Impatience’, ‘Irritability’ and ‘Extreme mental tension’. It is also one of the five ingredients in the ‘Rescue remedy.’ (Plants for a Future)

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6. Wakame (Undaria pinnatifida)
(currently not a threat in  Northumberland)

This is delicious in soups, tsunomono (vinegared seafood), etc. Commonly used in Japanese cooking. High in antioxidants and vitamins.

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7.  Dead Man’s Fingers or Green Sea Fingers (Codium fragile subsp. tomentosoides)

Invaded: stats from plantlife.org.uk
I suspect it is edible, but need confirmation.

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8. Pirri-pirri bur (Acaenia anserinifolia) a.k.a. bidgee-widgee
Invaded: Native to New Zealand. Suspected import in “contaminated” wool.
Sticks to you like sculptural velcro and breaks apart easily. Has made significant inroads on Holy Island and in norther Ireland.

It’s in the Rosaceae family; and according to Plants for a Future, the leaves can be used for tea and are Antiphlogistic; Diuretic; and Vulnerary. (Plants for the Future)

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9. Wireweed (Sargassum muticum) a.k.a. japweed
Invaded: TBD

Another lovely addition to salads, having little exploding flavours when eaten. Cooked with fish, scallops, made for each other. (foods wild)

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10. Water Chestnut (Trapa natans)
Invaded: TBD
note: Must be cooked before eating, the seed/fruit contain a toxin that is destroyed by cooking.

..floating annual aquatic plant, growing in slow-moving water up to 5 meters deep, native to warm temperate parts of Eurasia and Africa. They bear ornately shaped fruits that resemble the head of a bull, each containing a single very large starchy seed. It has been cultivated in China for at least 3,000 years for these seeds, which are boiled and sold as an occasional streetside snack in the south of that country.(wikipedia)

Singhara Flour / Water Chestnut Powder:
StarchWater Chestnut Flour is made from dried, ground water chestnuts. The nuts are boiled, peeled, dried then ground into flour.
The flour, which is actually a starch rather than a flour, is bright white fine powder.
It’s primary use is as a thickener. It is also used in Asian recipes to make batters for deep-frying.

Water Chestnut Flour gives a light crust when used for dredging, and stays white as a coating even when fried.
It is very different from “real” chestnut flour, which is sweet.
Cooking Tips: Mix with water first before adding to hot liquid as a thickener. (practically edible)

Singhara is Indian water-chestnut, triangular in shape, with thick red…ish green skin, with 2 small spikes at the top. It has milky white, lightly sweet flesh. It is eaten like a fruit when fresh, made into bhajies and curries when halfway mature and made into flour when completely mature and dry.
Recipe for Singhara Flour Halva

You can also make Singhara poori.

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