Staple seed crops from perennials
'Yes, alright, you do grow lots of different tasting fruits, flowers and leaves, but what about real foods? Something that will fill me up. You don't seem to grow any staple foods here.'
We get quite a few visitors to the plant project at Plants For A Future and the above comment has cropped up from time to time. Whilst it is possible to get good crops of leaves from perennial plants within a year or two of moving onto a new site, and there are several fruits that can yield within a few years, obtaining staple foods such as nuts, legumes and cereals from perennials can take considerably longer. There is also very little information about the potential of many of these plants to produce worthwhile crops in Britain. When you take into account that it can be 30 - 40 years before some nut trees to come into bearing from seed you begin to see the problems of looking for staple crops from trees.
Never the less, there are quite a number of species that can be grown with the confidence that in time they will provide good and reliable crops. Before looking at these, however, I would like to mention a few annual plants that can be used to fill the gap between planting the trees and obtaining a crop from them. Quinoa, Chenopodium quinoa is a plant that is becoming much better known. Related to our native weed fat hen, it produces good yields of very nutritious seeds that are a good source of a high quality protein and can be used in all the ways that rice is used. There are several legumes that yield good crops. The most reliable must be broad beans, Vicia faba, but French beans, Phaseolus vulgaris, can also produce good crops of seed in warm summers. One exciting potential crop for Britain is a lupin from S. America - Lupinus mutabilis is nutritionally very similar to soya beans but easier to grow and higher yielding in this country. Most forms have bitter tasting seeds, this bitterness can be removed by soaking the seed for 12 - 24 hours and changing the water 2 or 3 times. There are some varieties being developed that have sweet tasting seeds. Runner beans, Phaseolus coccineus, are perennials, the roots are hardy to about -5 c and if mulched will survive the winter in many parts of Britain. Yields, however, are lower in succeeding years than in the first year. There are also the various cultivated cereals such as wheat, oats, barley and rye.
There are quite a number of potentially high-cropping nut trees that can be grown in Britain but I am going to concentrate on those for which we can be most confident of obtaining good yields. For this reason I must discount almonds, Prunus dulcis, (they flower much too early and rarely yield well).
Walnuts, Juglans regia, can give good yields but this crop is also unpredictable. Mind you, walnut trees have so many other uses that I would strongly advise anyone with enough land to seriously consider planting out a small plantation. Some of its other uses include:- the sap is tapped in spring and used to make a sugar; a wide range of dyes can be obtained from various parts of the plant; an edible oil from the seed can also be used in soapmaking, paints, etc though it quickly goes rancid; the nuts can be used as a wood polish - simply crack open the shell and rub the kernel into the wood to release the oils then wipe off with a clean cloth; the dried fruit rind is used to paint doors, window frames etc (it probably protects the wood due to its tannin content); the crushed leaves are an insect repellent; a substance called 'juglone' is secreted from the roots of this tree, it has an inhibitory effect on the growth of many other plants; the fresh or dried bark of the tree and the fruit rind are dried and used as a tooth cleaner; the wood is a very valuable timber and is used for furniture making, veneer etc. With all these other uses, what does it matter if you don't get nuts every year!
There are many named forms of Cob-nuts and Filberts, Corylus avellana and C. maxima (derived in part from our native hazel) and these are a good staple to grow. Even these can be unpredictable because of the earliness of their flowering. They are relatively quick to come into bearing however, and usually give good yields.
One very good and reliable cropper, especially in the western part of Britain, is Araucaria araucana, the Monkey puzzle tree. This tree comes from S. America and the seed is a staple crop of the native Indians. Research carried out in the 1800's suggested that this tree is potentially heavier-yielding in Britain than our native hazel. The seed is about the size of an almond, it is rich in fat and has a nice mild nutty flavour. It is produced in a cone about the size of a person's head, each cone contains up to 200 seeds. Some reports say that the cone falls to the ground with the seeds inside it, others say that the seed is shed from the cone whilst still on the tree. A very wind- resistant tree, tolerating maritime exposure, it casts little shade and so can be used as the top storey of a forest garden. There are some drawbacks with this plant - it takes up to 40 years from seed before it comes into bearing and you need to grow at least one male tree for every 5 - 6 females in order to get seed but unfortunately it is impossible to distinguish males from females until they flower. However, there is a means of taking cuttings by using small adventitious growths that are sometimes found growing out of the trunk and so it is possible to obtain plants of known sex. It is also possible that these cuttings will fruit more quickly than seedlings. More research is needed into this subject.
Cephalotaxus harringtonii and C. fortunei are small conifers that look rather like our native yew (Taxus baccata). We have been checking these trees since 1987 and they have cropped well almost every year. The seed is a little smaller than an almond and is contained in a thick fleshy 'fruit' (botanically called an aril, but why should I bore you with that piece of information). This seed is eaten in Asia but is bitter unless fully ripe and even then is probably best cooked. The fruit, when fully ripe, is sweet and quite pleasant to eat, unripe it tastes like turpentine! The plants are very shade-tolerant (we have seen them carrying a heavy crop when growing in the quite dense shade of other conifers). They require a shady position if they are to do well when grown in the sunnier and warmer parts of Britain, though they succeed in a sunny position in the sheltered valleys of Scotland. They are quite slow-growing and we do not know how long it takes before they will fruit from seed. You need to grow at least one male plant for every 5 - 6 females.
Another coniferous nut tree attracting our attention is Torreya nucifera. This plant is a staple crop in parts of China, the pleasantly-flavoured seed is slightly larger than an almond and we have seen the tree carrying good crops on several occasions in the past few years. The fruit looks very similar to Cephalotaxus species, but it is not edible. The tree grows well in light shade, we do not know how old it has to be before it starts to yield.
Castanea sativa, the sweet chestnut, grows and fruits very well in Britain, though unfortunately our climate is not warm enough to produce the best quality large seeds. Even if the seed is somewhat smaller than the ones you can buy in the shops, the flavour is the same and overall yields in Britain are usually good. It is a very large tree, however, and is not the sort of thing you would want in your average back garden. C. pumila, the Chinquapin, might be an answer here, only growing about 3.5 metres tall and wide. Although the books say that it does not fruit in Britain, we have seen good crops on a plant about 15 miles west of London on several occasions in the last few years. The seed is rather small, but it is well flavoured. The chinquapin is a very good plant to grow in the light shade of pine trees, succeeding in sandy acid soils. Whereas most nut seeds are rich in fats, this genus produces seeds rich in carbohydrates and they can be used as an alternative to cereals in the diet.
Quercus ilex, the holm oak, grows well in most parts of Britain. A large spreading evergreen tree, it can also be trimmed and used as a hedge though it is unlikely to produce many of its edible seeds when grown this way. Very resistant to maritime exposure, it is often used to provide shelter in the windy gardens of Cornwall. The seed is similar to, but smaller than, our native oak and can be used in the same ways as sweet chestnuts (to which it is nutritionally similar). Trees usually fruit abundantly, the quality of the seed varies from tree to tree, the best are free of any bitterness and can be eaten raw or cooked. The sub-species Q. ilex ballota used to be cultivated as a food crop in Spain and Portugal. It is said to fruit less well in this country but I have seen good crops on a number of occasions.
There are many more nut trees with potential for this country, but when it comes to perennial cereals and pulses the situation is more restricted. Most perennial cereals tend to have one or more of the following drawbacks:- low yields, small seeds, difficult to extract. There is some research being carried out in N. America, but this is looking mainly at crops for arid areas and is not so relevant for Britain. Because crops are normally obtained in their first or second years growth, there is a large potential for selective breeding in order to produce more productive perennial cereals but, at present, we have only come across one species that has produced well. This is Secale montana a perennial rye that is believed to be the parent of the cultivated cereal rye, though the seed is somewhat smaller. Our original plants have been cropping since 1990 despite considerable neglect from us, yields are fair though much less than from the annual rye. We are selecting for plants with higher yields and larger seeds and would hope to be able to supply superior cultivars in future years.
Beckmannia eruciformis grows wild in swamps and shallow water, though it will tolerate drier soils, it also succeeds in saline soils. Plants can grow up to 1.5 metres tall but are much smaller in drier soils. The seed is very small but is easy to harvest and produced in abundance. It probably has the potential for improvement and has been used in the past for making bread.
Glyceria fluitans. Floating manna grass grows best in shallow slow-flowing or stagnant water, though it also succeeds in wet soils. It is about 50cm tall. Its rather small seed can be eaten raw or cooked and has a sweetish taste. The plant has occasionally been cultivated for its seed, this is considered a delicacy in some parts of Europe and was an article of commerce until well into the 20th century. A flour from the seed is said to make a bread little inferior to wheat bread, the flour can also be used as a thickener in soups etc when it imparts a sweet delicate flavour.
Wheat, Triticum aestivum, has a potential to perennate and there is at least one cultivar, called appropriately enough 'Perennial', that has been selected for this trait. It is said to yield well, though only a proportion of the plants live for a second or third year, however, and very few live longer than this. We have not as yet grown this cultivar. At present we feel that the oak and chestnuts mentioned above are the best substitutes for cereals, though they cannot be used in all the same ways as cereals.
The situation with peas and beans is somewhat more promising. There are a number of Caragana species, in particular C. arborescens, the Siberian pea shrub, that can yield good crops of edible seeds. The seed is about the size of a lentil and is somewhat tedious to harvest, but that can be tolerated since it is about the only thing you will have to do to the plant. This seed is very nutritious, containing about 12% fat and 36% protein. Although there have been suggestions that the seed contains toxic substances this has been discounted in more recent studies. C. boisii and C. fruticosa are closely related to this species and can probably be used in a similar way. C. brevispina has somewhat larger seeds, though these are more bitter than C. arborescens. Caraganas come from climates with much colder winters than Britain, but also with hotter summers, they therefore grow and fruit better in the east of the country. They do not really like very humid climates. Give them as sunny a position as possible and a well-drained soil. They are fairly fast growing, tolerate drought and poor soils, C. arborescens also succeeds in very alkaline soils.
Desmanthus illinoensis is a N. American perennial that is being evaluated by the Land Institute of Salina, Kansas, as an edible legume for growing with perennial grains in a non-tillage permaculture system. We have not yet grown the plant but reports say that it can self-sow to the point of nuisance and that its seed is rather bland. Both these points are positive, since it means that it crops well and that it can be easily flavoured with herbs etc for use as the protein part of a meal. Give the plant a sunny position in a well-drained soil.
Medicago sativa, Alfalfa grows very well in Britain so long as the appropriate rhizobium bacteria is present in the soil. This bacteria lives on the roots in a symbiotic relationship with the alfalfa and converts atmospheric nitrogen into a form that alfalfa can utilize, thus improving the growth of the plant. Alfalfa seeds are small and fiddly, but are often used for sprouting, making a very nutritious food. The seed can also be ground into a flour and be mixed with wheat to make a protein-rich bread. The young shoots can also be eaten raw or cooked. A drying oil from the seed is used in making paints etc. The plant is very deep rooted and makes an excellent long-term green manure.
The database has more details on these plants: Araucaria araucana, Beckmannia eruciformis, Caragana arborescens, Caragana boisii, Caragana brevispina, Castanea pumila, Castanea pumila ashei, Castanea sativa, Cephalotaxus fortunei, Chenopodium quinoa, Corylus avellana, Corylus maxima, Desmanthus illinoensis, Glyceria fluitans, Juglans regia, Lupinus mutabilis, Medicago sativa, Phaseolus coccineus, Phaseolus vulgaris, Prunus dulcis, Quercus ilex, Quercus ilex ballota, Taxus baccata, Torreya nucifera, Triticum aestivum.