Beyond potato – Arrowroot & cassava
3 Apr 2022
While potatoes grow in this area, they aren’t that reliable for beginners and need a bit of work and attention. If you want a set and forget kind of growing with a potato-like result at the end, these two plants are some of the starchy tubers to become familiar with. Each of these is super easy to grow. They are basic to reliably propagate. They are very robust and hardy through drought and flood. The learning is more in preparing them for eating. Once you get the hang of them, they are very much potato substitutes.
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Arrowroot / canna lily / achira / edible canna / Queensland arrowroot
Canna edulis / indica / discolor
As far as growing is concerned, this is an ideal plant for beginners. Drought and flood hardy, arrowroot is a true ‘stick it in the ground and walk away’ kind of food plant. And then it grows like the clackers!
Getting familiar with cooking it is the challenge. Ensuring you have a good edible variety and not a somewhat palatable weedy nightmare is another piece of the puzzle. Note that there are a huge number of ornamental canna varieties that are not considered edible. Find a reliable source.
Classification wise, the canna family has undergone a consolidation in recent years. Many canna species are now thought to be varieties instead, and this is true of the previous distinctions of C. edulis vs C. indica which might both now be C. discolor. Oh the ologists! Any of these are edible. Flowers can be red, yellow or sometimes orange. Foliage is green, sometimes with red portions. There’s a lot of variation. Speaking broadly, the varieties with the giant and magenta-flushed tubers that poke out of the ground, are considered better eating than those with the smaller white underground tubers. The large tubered ones do not tend to go to seed. The smaller tubered ones seed prolifically and are an absolute nuisance. The seeds are so hard they are used as buckshot and stay viable for up to 550 years! Nuisance edible varieties are raging at Northbank Community Gardens.
To grow arrowroot for eating, it likes plenty of water and sun. It is a weed of waterways and swampy ground. The plant stands a good 2m tall, with leaves up to 60cm long. It will survive in dry shady compacted soil though that won’t make good eating tubers. Grow it fast for the least amount of stringyness. This is a hardy plant who can hold its own against grass and bananas who are both hungry thugs. I’ve found it has a rather competitive root system that extends about 60cm sideways from the tubers. Keep it at a distance to other plants you care about.
Plant and pick at any time of year. Tennis ball sized tubers can be snapped off for eating whenever you want (they grow poking out of the ground). When the clump becomes too crowded the stems begin to grow spindly. Dig up and divide. Replant the small tubers. Compost the brown old oversized ones. Eat the medium sized ones.
The tubers and the young shoots are the main parts we eat. How palatable these are depend on the variety you have.
Young shoots about an inch tall can be sliced thin and cooked. Taller ones may need skinning back to the white core first. This should be a pleasant eating experience, but some varieties are like trying to eat a mouthful of dental floss. Unripe seeds can be roasted. Ripe seeds will break your teeth.
There are many ways to eat the tuber. It is edible raw, though bland. It can be stirfried, boiled, steamed or baked. The eating is similar to an unsweet waterchestnut until it is thoroughly cooked, when it passes admirably for potato. Arrowroot needs to be cooked for at least twice as long as potato to be potato-soft.
Young tubers have more flavour and are far less stringy than older ones. Any stringyness is on the outside of the tuber. When peeling, you can feel the difference with a paring knife. Sometimes a centimetre of fibre has to be peeled off the outside. Submerge peeled or sliced tubers in water otherwise they turn brown. Some people like to peel, slice and soak arrowroot for a number of hours before cooking to leach out the excess starch. They find this improves the flavour.
When sliced thin and stirfried the crispyness is good. In a gratin, baked with cheese and potato it is indistinguishable from potato. Cut the arrowroot thinner than the potato pieces so it cooks quicker.
But the best way to eat arrowroot tubers is to roast them. Leave the skin on. Optionally, rub in oil and salt and wrap in an arrowroot leaf. When they are done, scoop out the soft and sweetened innards and leave the outer fibrous (and now hardened) skin behind.
The tubers only store for a few days once picked. Leave them in the ground until you are ready to cook them. Otherwise, keep them in the fridge either unpeeled, or peeled and under water. Change the water as needed.
For arrowroot the thickening flour, there are a number of plants which can be used to make this. Queensland arrowroot is not the one usually used commercially any more but it was a settler-era crop and the arrowroot weed problem in SE Queensland likely comes from this former industry. The famous Arrowroot Milk biscuits are from this era too, using this plant as a main ingredient.
To make arrowroot flour, grate or pulverise the root and soak in water. Squeeze the pulp so the starch comes out in the water. The flour will settle to the bottom and the pulp can be drained off the top. Drain off the excess water and pour the white flour into trays 1 – 2 cm thick for evaporative drying. Dry (in the sun) until soft and powdery.
Arrowroot has a huge number of uses beyond eating. The flowers are loved by pollinators, regardless of whether they set seed. The leaves make great biodegradable plates. They make an ideal wrap for cooking food such as fish or their own tubers. Leaves and stems are up to 10% protein and so are good food for chooks, goats, cows and donkeys. The leaves also hold a lot of water which means they make great mulch for thirsty plants, covering the soil and giving a drink at the same time. They make so many leaves you will always have compost or general mulching material. They can be cut right back several times a year at least for this. As a plant, arrowroot is useful as a windbreak or shade shelter. Or even as a weed barrier along with some other plant friends like comfrey and lemongrass. One point to note, arrowroot can get a rust problem so don’t use arrowroot to mulch arrowroot.
Cassava / manioc / yuca (not yucca)
Obscure here but a staple for nearly a billion people, cassava is another of the world’s most drought tolerant food plants. It has almost no soil or watering or fertiliser requirements. This is a perennial plant and we can eat the leaves and the swollen roots, though they all MUST be cooked to remove cyanide. Yup, cyanide! The window for picking is very wide. The nutrient density is high. This is a terrific food resilience plant. It’s hard for a beginner to go wrong trying to grow this.
The only soil requirement for cassava is that it must be well drained, and then cassava will cope with rainfall between 50 and 5000mm. We average about 2100mm. Around here, grow it up on a mound of about half a metre for good drainage in our flooding rains. This also makes digging up the roots easier. Soil can be low in fertility and cassava will still grow well. pH doesn’t matter. Clay or sandy doesn’t matter, though it does grow better with larger roots in lighter soils.
Planting is as simple as it gets. Cut sticks from the stem. They need to be about 25cm long and at least 1cm thick, with several nodes on them, and brown and woody not green and soft. That covers most of the plant stem! Ideally these pieces have their ends cut on a diagonal for more area for root growth, though it doesn’t matter if they are cut straight. Plant the sticks horizontal or vertical or have two angled at 45° like a cross. In my limited trials I’ve found vertical to be best so far. Sticks should be pushed at least 6cm into the ground, up to 2/3 of the stick length. Horizontal planting is about 6 – 10cm underground. Space plants a metre apart. Choose a frost free position. It’s a tropical plant whose home range is within 30° of the equator. In this area cassava dies down to a leafless stick in July / August. That’s a good time to dig it up and prep for replanting from September or anytime after frost.
This is a perennial plant with a very wide harvesting window.
The leaves can be used as a spinach after boiling -lid off in a ventilated area- for 10 – 15 minutes to make them safe to eat. Just matured leaves are said to be best.
The swollen roots are the main part we eat. There are usually 4 – 8 fat roots per plant, each the size of a massive sweet potato. Above ground is a 2 – 4m tall skinny stick of a tree looking a lot like a pawpaw / papaya tree. Sometimes it can have multiple stems. The roots take 8 months to grow to edible maturity, which means April at the earliest. But, they can be left in the ground for up to 8 years and still be edible. The roots do become more and more fibrous as they age so the best eating age is in the 8 – 15 month range. If you can’t cut it with a sharp knife it’s too old, it won’t soften enough with cooking to be edible. You can bandicoot for a single tuberous root or pull the entire plant up for a feast. You may compete with bandicoots, rats and bush turkeys for the roots.
These tuberous roots don’t store well at all once cut from the plant. They only last for 3 – 5 days uncooked, or 10 in a fridge. To extend this the roots can be de skinned and frozen if you have the space. A lot of cassava is grated and dried and ground and used as a very lovely gluten free flour.
To cook fresh cassava roots, peel off the skin and the fibrous outer layer of a few mm thick using a knife. The layering is quite obvious and peels away cleanly and easily from the soft insides. Often there is a thin fibrous cord running down the centre which is too tough to eat too. Chop the insides into chunks and boil -lid off in a ventilated area- for 10 – 15 minutes. This makes them safe to eat. Throw the water and the skins away as these contain the cyanide. In the compost is fine. Then use the cooked insides as a potato substitute as mash, in soups, in stews etc. Remember, don’t cook the cassava in the stew etc. Cook it first and add afterwards. Its cooking water needs to be thrown away. Cassava makes great chips! The flavour is different but potato-like. The nutrient density may take you by surprise. Cassava is at least twice as nutritious as potato and it really is twice as filling.
Different varieties of cassava have different levels of cyanide. Technically it contains cyanogenic glycosides which break down to form cyanide when its cells are disrupted. Broadly, cassava varieties are divided into sweet (not actually sugar sweet) vs bitter. The sweet varieties have about 50 times less cyanide than the bitter ones. Sweet varieties are safe to eat after cooking first as above. Bitter ones need a much more involved process of fermenting or soaking for days and washing before roasting or cooking to make them safe and people do die if bitter cassava is not processed properly.
Testing the cheekiness. The bitter zapping effect associated with high-cyanide cassava is not directly related to the cyanide levels, it’s only a tendency that bitterness and cyanide levels rise together. This means that testing the bitterness is not a reliable indicator of how much cyanide is present.
Drought, high levels of soil nitrogen and bashing the roots will each increase the levels of cyanide. Purple streaks in the roots indicate concentrated hydrocyanic acid and these should be discarded. There is no reliable home test for discerning sweet from bitter cassava. Obtain your cassava from a trusted source of a sweet variety!
Big thanks to
Joy Foley, Mark Graham from Bellingen Nature Tours, Nick Radford from Bellingen Permaculture, Kyles Woodbury formerly of The Vegie Gardener, Carole & Phil Helman, John Vernon and the Bellingen Seedsavers blog, Pete Bufo, Charles Filet, Cath Eaglesham.
Supported by Bellingen Shire Council via the Bellingen Shire Disaster Recovery and Resilience Grant Program Funding
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