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Useful Plants from Robert Nold’s “High and Dry”

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One of the more challenging environments for food production is cold and arid. I’ve been investigating useful perennial plants for that climate for many years. A few years ago I purchased Robert Nold’s High and Dry: Gardening with Cold-Hardy Dryland Plants. Robert isn’t interested in growing these plants for food, but he has an incredible wealth of knowledge and years of experience in growing plants in his Littleton, Colorado garden with 10″/250mm of precipitation a year and -10F/-23C winter temperatures.

I was fortunate to be able to visit Robert and his garden with a class last year. It was fascinating to see his collection, and I was struck by the beauty of these tough high desert survivors.

Robert’s book is quite remarkable and offers great information on growing and propagating these species. He doesn’t say which are edible or otherwise useful though. This article is intended as a “key” to help permaculturists and edible landscapers utilize his book to select species for a cold, arid perennial food production system. I’ve already cross-indexed them with other resources for you. High and Dry also has much to say on the subject of gardening in cold, dry climates in general – for example, he reports that most of these plants grow in soils with little or no organic matter in their native habitats, and are more vulnerable to disease in compost-enriched soils.

This article features many of the useful species from High and Dry. Get a copy and read it to learn all about his experiences growing them. All of these species have survived Bob’s test conditions of 10″/250mm of rainfall a year and -10F/-23C. All are native to the western United States, and some to adjacent Canada and Mexico as well. Of course there are many other useful species, native and not, that are suited to this area. Growers in other cold, dry regions (particularly in Central Asia) may also want to grow some of these species.

My sense is that these might represent the things you grow farther from home, while close by you’d have water-loving crops like peaches and apples watered by greywater and roofwater (or plain old drip irrigation).

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Robert’s front yard with Cercocarpus (nitrogen), Lycium (fruit), Quercus (acorns), Cylindropuntia (fruit), Yucca (fruit), Elaeagnus (nitrogen), Opuntia (fruit, vegetable) and more. This is a zero-irrigation garden area in a region with -10F/-23C and 10″/250mm of precipitation per year, full of edible and useful plants (though he grows them only for beauty). The acorn from this oak (Q. undulata I believe) was the best I’ve ever had. Littleton, Colorado.
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A piece of Robert’s back garden with Cylindropuntia (fruit), Yucca (fruit), Cercocarpus (nitrogen), Pinus (nuts) , and Amorpha (nitrogen). This is a pattern that a cold, arid food forest can follow. Littleton, Colorado.

TREES

Few trees grow in the high and dry country, and fewer still are much use to us in the food forest. Here are some good ones recommended by Nold. Pinyons are slow to grow and don’t bear annually but can grow where nothing else will. Mesquites are delicious and nitrogen fixing. We could use people identifying and propagating good forms of oak, mesquite, and pinyon.

Latin Name Common Name Uses Functions
Cercocarpus ledifolius mountain mahogany   nitrogen-fixer
Pinus edulis, P. monophylla pinyon pine nuts  
Prosopis glandulosa honeypod mesquite staple pods, honey plant, coppiced firewood nitrogen-fixer, fodder pods
Quercus emoryi, Q. hybrids, Q. undulata “sweet” acorn oaks    
Robinia neomexicana New Mexico locust edible flowers, firewood nitrogen-fixer
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IMG_6586 New Mexico locust is a nitrogen-fixing, coppiced firewood plant. Sedalia, Colorado.

Cercocarpus ledifolius is a very tough nitrogen-fixer, handling arid conditions and -50F/-45C! Robert’s garden.

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Pinyon pine savannah, with Utah serviceberry. Near Reno, Nevada.
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Honeypod mesquite has excellent edible pods, fixes nitrogen. Some forms hardy to -10F/-23C, this is the hardiest mesquite. Image courtesy Wikimedia Commons.
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Emory oak is one of the few I’ve eaten that can be enjoyed free of bitterness. Image public domain.

SHRUBS

This region excels in useful shrubs, including many edible berries and a large number of legume and non-legume nitrogen-fixers.

Latin Name Common Name Uses Functions
Amelanchier alnifolia, A. utahensis serviceberry berries  
Amorpha fruticosa, A. nana false indigo pesticide nitrogen-fixer, contour hedgerow
Ceanothus fendleri, C. velutinus snowbrush   nitrogen-fixer
Cercocarpus montanus mountain mahogany   nitrogen-fixer
Elaeagnus commutata silverberry soap nitrogen-fixer
Fallugia paradoxa Apache plume   nitrogen-fixer
Lycium pallidum wolfberry fruit (native goji)  
Prunus americana American plum fruit  
P. besseyi sand cherry fruit  
P. virginiana chokecherry fruit  
Purshia tridentata bitterbrush   nitrogen-fixer
Ribes aureum, R. cereum, R. odoratum currants fruit  
Shepherdia argentea, S. canadensis buffalo berry fruit (not fantastic), soap nitrogen-fixer
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The lovely nitrogen-fixer Amorpha nana with banana yucca. Denver Botanic Garden.
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Serviceberries are the blueberry of the arid west. Montreal Botanic Garden.
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Arctostaphylos patula and others make excellent evergreen groundcovers. Fruit edible but not fantastic. Denver Botanic Garden.
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Cercocarpus montanus, one of many in this nitrogen-fixing genus. Colorado National Monument.
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Eleagnus commutata, fruit terrible but used to make soap. Nitrogen-fixer. Robert’s garden.
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Fallugia paradoxa, Apache plume, a stunningly ornamental native nitrogen-fixer. Denver Botanic Garden.
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Lycium pallidum, our spicy-fruited native goji (one of many native American gojis in fact). Robert’s garden.
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Mahonia repens, creeping Oregon grape, a nice evergreen groundcover with small, sour fruits. Denver Botanic Garden.
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American plum, Prunus americana. Doesn’t bear well every year but when it does wow! Littleton Colorado.
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Sand cherry Prunus besseyi, extremely tolerant of arid conditions and heavy deer and elk browsing. Nice fruit but not great. Please find a good one and propagate it! Holyoke, Massachusetts.
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Bitterbrush, Purshia spp., nitrogen-fixer for cold arid lands. Near Reno, Nevada.
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Ribes aureum, buffalo or clove currant, heavy bearer in dry conditions. Holyoke, Massachusetts.
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Buffalo berry, a spreading nitrogen fixer. Some varieties taste better than others, I’ve never met anyone who said they were wild about the flavor though. Image Wikimedia Commons.

SUCCULENTS

This group includes cacti and “woody lilies” like agaves and yuccas. There are many useful species in this group. I’m not aware of any prickly pears with inedible fruit or pads, for example – though many are so small or spiny as to be not worth the trouble. A form of O. phaeacantha called “Mesa Sky” is noted for having particularly good fruit, while O. basilaris var. aurea is relatively spineless for nopale (edible cactus pad) production. I’m unaware of improved agaves or banana yuccas but would love to see people out there testing, selecting, and propagating them!

Latin Name Common Name Uses Functions
Agave parreyi agave swollen base cooked just before flowering living fence
Cylindropuntia imbricata, C. whippleyi cholla cacti flowerbuds, fruit living fence
Echinocereus engelmannii, E. stramineus strawberry cacti fruit  
Mammillaria heyderi, M. wrightii pincushion cacti fruit  
Opuntia basilaris, O. englemannii, O. fragilis, O. macrocentra, O. phaeacantha, O. polyacantha prickly pear cacti fruit, nopale vegetable pads living fence (some)
Pediocactus simpsonii hedgehog cacti fruit  
Yucca baccatta banana yucca cooked fruit, fiber living fence
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Cylindropuntia whipplei, with edible flower buds and fruit, surely as fine a living fence as you could ever want! Grand Junction, Colorado.
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Echinocereus species are known as “strawberry cactus” for their small, sweet fruits. Denver, Colorado.
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Opuntia basilaris var. aurea, the spineless beavertail prickly pear cactus, with edible fruit and nopales. Spinelessness definitely a plus for harvest! Note small glochid spines still present. Denver Botanic Garden.
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Fruits of banana yucca are cooked as a semi-sweet vegetable. Also a fiber crop. Image Wikimedia Commons.

 

HERBACEOUS PLANTS

The region excels in edible roots. Though I’ve not included them here, Nold lists a hundred or so plants in the aster family, which attract beneficial insects.

Latin Name Common Name Uses Functions
Amorpha canescens leadplant tea nitrogen-fixer
Brodiaea spp.   bulbs  
Callirhoe involucrata purple poppy-mallow roots groundcover
Calochortus spp. Sego lily roots  
Cucurbita foetidissima buffalo gourd seeds groundcover
Dalea spp. prairie clover   nitrogen-fixer
Dichelostemma spp.   bulbs  
Erigeron flagellaris fleabane   attracts beneficial insects, groundcover
Helianthus maximiliani Maximilian sunflower shoots, seeds attract beneficial insects
Ipomoea leptophylla manroot roots  
Lewisia spp. bitterroot roots  
Lomatium spp. biscuit roots Roots attract beneficial insects
Lupinus spp. lupine   nitrogen-fixer
Oryzopsis hymenoides Indian ricegrass seeds  
Phacelia tanacetifolia scorpion weed   attracts beneficial insects
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Purple poppy-mallow, groundcover with edible roots.Near Moab, Utah.
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Sego lily, edible roots. Sedalia, Colorado.
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Buffalo gourd, groundcover perennial squash with edible seeds. Image Wikimedia Commons.
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Maximilian sunflower, edible shoots and seeds. Birmingham, Alabama.
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Manroot morning glory, wild relative of sweet potato with enormous edible roots. Image Wikimedia Commons.
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Biscuitroot, edible roots and attracts beneficial insects. Holyoke, Massachusetts.
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Phacelia, grown commericaly for beneficial insects on farms in Europe but native to dry western North America. Near Reno, Nevada.
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Indian ricegrass, important wild staple grain historically and a minor perennial crop today. Moab, Utah.

 

 

 

 

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Legume Trees with Pods Edible by Livestock

This article is an excerpt from my forthcoming book Carbon Farming: A Global Toolkit for Stabilizing the Climate with Tree Crops and Regenerative Agriculture Practices, and is part of a series promoting my kickstarter campaign to raise funds with which to complete the book. You can pre-order a copy and help make it possible for me to get this book out soon.

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This painting by Joaquin Sorolla y Bastida shows sheep enjoying the shade and dropped pods of an ancient carob tree. Courtesy Wikimedia Commons.

Rotational grazing is one the most powerful tools we have to sequester carbon through agriculture. We can increase its carbon-sequestering capacity, and its livestock production power, by adding widely-spaced trees. This practice of integrating trees with grazing is called silvopasture. Studies have shown that in many cases trees actually increase the productivity of pasture beneath them, especially trees that cast light shade.

This article is about a particular kind of silvopasture, where the trees literally drop food to the livestock grazing below. Around the world there are many farming systems that utilize this concept, most famously the dehesa of Spain and Portugal which produces gourmet acorn-fed pork. Here I’m narrowing the focus a bit more, to legume trees that drop nutritious pods to the ground for ruminant livestock like cattle, sheep, and goats. There are “fodder pod trees” like this for most of the world’s climates.

Pods of carob, a tree for Mediterranean climates. Great livestock fodder and edible for humans as well.
Pods of carob (Ceratonia siliqua), an ancient Mediterranean crop. Great livestock fodder and edible for humans as well. Courtesy Wikimedia Commons.

These trees are providing more than just food for animals. Livestock enjoy the shade they provide, especially in the tropical sun. Many of these trees fix nitrogen. Some even have pods edible for humans.

Unfortunately not all of these pods fall to the ground when ripe, some must be knocked off the tree with poles, increasing labor requirements. To my knowledge there has been little or no breeding of these trees for the purpose of feeding livestock. The foliage of many serves as a fodder, and some make excellent firewood as well.

The great majority of these species hail from semi-arid Africa savannahs, but this may in part result from a lack of research in other regions. Surely there are many, many more. Savannahs would be the best place to search for such species as they have coevolved with large grazing and browsing animals. An asterisk (*) indicates pods also edible by humans. Sources: Nitrogen Fixing Tree Association NFT Highlights and World Agroforestry Center Agroforestree Database.

Latin Name Climate Native Range Nitrogen Fixation
Acacia leucophloea semi-arid tropical lowlands Asia yes
Acacia nilotica semi-arid tropical lowlands Africa yes
Acacia saligna semi-arid tropical lowlands Australia yes
Acacia senegal semi-arid tropical lowlands and highlands Africa yes
Acacia seyal arid to semi arid tropical lowlands Africa yes
Acacia tortolis arid to semi-arid tropical lowlands, highlands Africa yes
Adenanthera pavonina semiarid to humid tropical lowlands Asia yes
Cassia grandis humid lowland tropics tropical Americas some
*Ceratonia siliqua Mediterranean Mediterranean no
Enterolobium cyclocarpum     yes
*Erythrina edulis semi-arid to humid tropical highlands Andes yes
*Faidherbia albida arid to humid tropical lowlands and highlands Africa yes
*Gleditsia triacanthos cold humid and arid, Mediterranean, tropical highlands North America no
Newtonia buchananii humid tropical lowlands and highlands Africa no
*Parkia biglobosa semiarid to humid tropical lowlands Africa yes
*Parkinsonia aculeata arid to semiarid tropics and subtropics Americas no
*Piliostigma thongii semiarid tropics Africa yes
Pithecellobium dulce semi-arid to humid tropical lowlands Americas yes
Prosopis africana     yes
*Prosopis alba semi-arid tropics South America yes
Prosopis chilensis semi-arid tropics and subtropics South America yes
Prosopis cineraria arid to semi-arid tropical lowlands Asia & Middle east yes
*Prosopis glandulosa arid to semi-arid, subtropics to cold North America yes
*Prosopis juliflora     yes
*Prosopis pallida semiarid tropics South America yes
Prosopis tamarugo arid tropics South America yes
Samanea (= Albizia) saman semi-arid to humid tropical lowlands tropical Americas yes
Senna singueana semiarid tropics Africa no

Again note that nitrogen-fixing legumes are often likely to escape from cultivation. Always investigate your regional native plant resources first. I’m quite certain that there are tens or hundreds more species that produce fodder pods, as well as many more that drop food of one kind or another to ruminants. For example there are many more species of honey locust (Gleditsia) in Asia.

The pods of Acacia nilotica, from African semi-arid savannahs. Courtesy Wikimedia Commons.
The pods of Acacia nilotica, from African semi-arid savannahs. Courtesy Wikimedia Commons.
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Cassia grandis, from the humid tropical Americas. Courtesy Wikimedia Commons.
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The North American honey locust (Gleditia triacanthos), a good choice for cold temperate climates. Courtesy Wikimedia Commons.
The sweet pods of mesquite (Prosopis glandulosa), a nitrogen-fixing tree for cold, arid landscapes.
The sweet pods of honey mesquite (Prosopis glandulosa), a North America nitrogen-fixing tree for cold, arid landscapes. There are mesquites throughout the dry Americas as well as native species from Africa and Asia, for highlands and lowlands, arid and semi-arid climates. Courtesy Wikimedia Commons.

 

 

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Siberian Pea Shrub – a Potential Perennial Bean for Cold and Arid Regions

This article is an excerpt from my forthcoming book Carbon Farming: A Global Toolkit for Stabilizing the Climate with Tree Crops and Regenerative Agriculture Practices, and is part of a series promoting my kickstarter campaign to raise funds with which to complete the book.

Siberian Pea Shrub (Caragana arborescens). This shrub from Siberia and other semiarid parts of Northeastern Asia is remarkably cold hardy – tolerating temperatures below -40, the frigid temperature where Celsius and Fahrenheit overlap. It is widely used for windbreak, nitrogen fixation, livestock fodder, and erosion control in the world’s cold regions. It is particularly common in the Canadian prairies, where hundreds of miles of pea shrub windbreaks have been planted.

Siberian pea shrub produces fairly high yields of small beans. Canadian farmers use the beans as survival food, boiling them in several changes of water in lean years to remove the bitterness. That doesn’t quite meet my definition of edible. However, Facciola’s Cornucopia: A Source Book of Edible Plants reports the dry beans contain up to 36% protein – very similar to soybeans.

Siberian pea shrub loaded with beans at Central Rocky Mountain Permaculture Institute.
Siberian pea shrub loaded with beans at Central Rocky Mountain Permaculture Institute.

Somewhere out there in the wilds of Siberia or in a lonely windbreak in Saskatchewan, the perfect edible pea shrub may very well already exist. This crop offers the potential for a long-lived woody protein crop for the world’s boreal forests and grasslands, semi-arid mountains, and other inhospitable climates. Screening existing populations for edibility, and breeding lines of truly edible pea shrubs should be a high priority for researchers in cold and arid climates, including backyard and amateur breeders. Breeding techniques were worked out in the 1960s in Canada for shelterbelt purposes (Cram, E.H. “Breeding and Genetics of Caragana”, The Forestry Chronicle, p. 400-401 (1969)), which gives us a head start. This species has naturalized in some parts of the US and Canada.

 

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Resources for Gardening with Edible Native Plants of the Eastern Deciduous Forest of North America

Recent decades have seen excellent work in prioritizing gardening with native species. However, most all–native gardens are not sufficiently ecological in that they do not provide the food and other needs of human inhabitants, nor accept and cycle their wastes. The ecological garden must embrace a wider perspective that de–externalizes the ecological footprint of the modern lifestyle, from the global food system to the fossil fuels that prop up our way of life.

There’s been lots of conflict between the native plants and permaculture wings of the environmental movement over the use of non-native useful plants. I’m sure we will continue to argue over particular species like hardy kiwifruit for decades to come. What we rarely focus on, though, is the great amount of common ground we actually share: useful native plants.

Northeastern Indians wild–managed, cultivated, and domesticated native plants in this region for millennia. Many native people still do, like the wild rice harvesters of the lakes region. We have an excellent palette of useful native species to work with. In my writing and teaching in the last few years I’ve been promoting this idea and finding that few people on either end of the conversation have truly explored the potential of our native flora. Few eastern native plants are available in our supermarkets: wild rice, grape jelly, sunflower seeds, pecans, blueberries and cranberries are among the exceptions. We need to learn, grow, and domesticate useful native species to serve as an anchor of a truly ecological society. And we will surely continue to need to use some species from outside the region to fill the gaps and provide a more diverse and productive landscape.

I propose an alliance between our branches of the ecological movement, promoting the great number of species that represent the overlap of our areas of concern. We both agree that non-useful, ornamental species from outside the region should be at the bottom of anyone’s species selection criteria. A platform for this new agenda might choose the blueberry as its emblem–a native edible crop that is an outstanding ornamental in all four seasons and an important anchor for the food chain through its hosting of numerous moth and caterpillar larvae.

For some forward-thinking projects, this discussion is about to become very grounded in reality. New buildings certified by the Living Building Challenge (a revolutionary new green building certificate that leaves LEED in the dust) are required to produce food on at least a third of the landscape in recognition of this ecological necessity. Will sites choose the hard–line but deeply interesting and educational option of growing only native food plants? Native to the Northeast, their state, or even their county? Or might they choose to also incorporate some familiar and better-producing fruits and vegetables in the mix, including known naturalizers like carrots and apples? I look forward to a lively discussion.

I’ve posted a list of over 200 useful perennial Useful Native Species of the Eastern Forest (including sixty native to Hampshire County) here. You can also find in my blog archive an article called “All Nitrogen Fixers Are Not Created Equal”, which reviews the pounds of nitrogen per acre fixed by native and non-native species of the eastern forest region, offering objective criteria for selecting superior native nitrogen fixers. I’ve also posted a table of eastern native plants that were wild-managed, cultivated, or domesticated by native people in the pre-colonial era below. Please use these tools to explore the uses and assess the current state of domestication of our native flora. You may also enjoy my article and video about growing out and eating ancient native annual crops. I think they show the potential and current limitations of the subject.

 

INDIGENOUS MANAGEMENT and CULTIVATION of

EASTERN FOREST PLANT SPECIES

 

Sources: Foraging and Farming in the Eastern Woodlands (ed. C. Margaret Scarry), Food Plants of the North American Indians (V. Harvard), Some Ecological Aspects of Northeastern Indian Agroforestry Practices (Karl Davies), Forgotten Fires (Omer Stewart), Cultivated landscapes of North America (William Doolittle), Giant Cane: Arundinaria gigantea (USDA NRCS).

LATIN NAME COMMON NAME WILD-MANAGED CULTIVATED DOMESTICATED
TREES        
Carya spp. Hickories & pecans Burning Yes  
Castanea dentata American chestnut Burning before harvest    
Juglans spp. Butternut & black walnut Burning    
Morus rubra Red mulberry   Yes  
Quercus spp. Oaks burning    

 

LATIN NAME COMMON NAME WILD-MANAGED CULTIVATED DOMESTICATED
SHRUBS        
Arundinaria giganteaa Canebrake bamboo Burning Yes  
Corylus spp. Native hazels Burning, pruning    
Ilex vomitoria Yaupon holly   Yes  
Prunus Americana American plum   Yes  
Vaccinium angustifolium Lowbush blueberry Burning Yes  

 

LATIN NAME COMMON NAME WILD-MANAGED CULTIVATED DOMESTICATED
VINES        
Amphicarpa bracteata Hog peanut   Semicultivated  
Apios americana Groundnut   Yes Partially
Passiflora incarnata Maypop passionfruit   Semicultivated  
Phaseolus polystachios Thicket bean   Semicultivated  
Vitis spp. Grapes   Yes  

 

LATIN NAME COMMON NAME WILD-MANAGED CULTIVATED DOMESTICATED
PERENNIALS        
Helianthus tuberosa Sunchoke   Semicultivated Yes
Physalis spp. Perennial ground cherries   Semicultivated  
Phytolacca americana Pokeweed Yes    

 

LATIN NAME COMMON NAME WILD-MANAGED CULTIVATED DOMESTICATED
ANNUALS        
Amaranthus spp. Amaranth   Semicultivated  
Ambrosia trifida Giant ragweed   Semicultivated  
Chenopodium berlandieri Chenopod   Cultivated Yes
Cucurbita pepo ovifera Acorn and zucchini squash   Cultivated Yes
Euphorbia maculata Spurge   Semicultivated  
Helianthus annuus Sunflower   Cultivated Yes
Iva annua Sumpweed   Cultivated Yes
Mollugo verticillata Carpetweed   Semicultivated  
Phalaris caroliniana Maygrass   Semicultivated Yes
Physalis spp. Annual ground cherries   Semi-cultivated  
Polygonum erectum Knotweed   Cultivated Yes
Portulaca spp. Native purslanes   Semicultivated  
Rumex spp. Native docks    Semicultivated  
Solanum spp. Black nightshade   Semicultivated  
Stellaria spp. Native chickweeds   Semicultivated  
Strophostyles helvola Woolly bean   Semicultivated  

 

LATIN NAME COMMON NAME WILD-MANAGED CULTIVATED DOMESTICATED
AQUATICS        
Nelumbo lutea Native lotus   Semicultivated  
Orontium aquaticum Golden club   Semicultivated  
Peltandra virginica Tuckahoe   Semicultivated  
Zizania aquatica Wild rice Intensive wild management    

 

 

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Nitrogen fixing podocarpus with Rhizobia partner!

Thanks to Taylor Nelson for pointing out that Podocarpus macrophyllus, in the Conifer division, fixes nitrogen. In fact it has Rhizobium in the roots but does not have nodules and may not fix very much nitrogen. Edible fruit! Talyor also mentioned that some South American Proteaceae may fix nitrogen as well.

Perhaps my hypothesis still holds if we only count nodules, but this blows my theory out of the water a bit. Which is cool!

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All Nitrogen Fixers Are Not Created Equal

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Nitrogen fixing species are a cornerstone of food forestry and other permaculture practices.  Through a partnership with symbiotic organisms in their roots, these plants can turn atmospheric nitrogen into nitrogen fertilizers useful to themselves but also becoming available to their neighbors over time through root die back, leaf fall, and chop and drop coppice management. While it does not replace the need to bring in phosphorus, calcium, and other nutrients depleted by harvests, this strategy provides a free source of an essential fertilizer.

Martin Crawford’s Creating a Forest Garden and Nitrogen Fixing Plants for Temperate Climates are excellent resources for calculating the percentage of nitrogen fixtures needed in order to supply all required nitrogen just from plants. Martin estimates this at 25 to 40% of plants in full sun or 50 to 80% of plants in partial shade, depending on the nitrogen needs of the crops being grown.

Now I’m going to throw another wrench into your calculations. I’ve known for some time that the amount of nitrogen fixed varies widely among species, but I recently discovered that the USDA plants database gives information about the amount fixed about many, many species native and naturalized to the United States. Check out their advanced search page to select species for your area. They classify species as HIGH (160+ lbs/acre), MEDIUM (85-160lbs/acre), and LOW (1-85lbs/acre). Note that there are a few species that might represent data entry errors (for example Phragmites is listed as a nitrogen fixer, though I’ve been unable to find another reference to this being the case). I spoke to Martin, who replied that he based his assumptions on an average of 100 kg/ha (88 pounds per acre), basing his estimate in the “medium” category. Thus using “high” nitrogen fixers would allow less space to be used on fertility and more on crops.

It’s interesting to note that many of the most hated naturalized species turn out to be incredibly efficient nitrogen fixers. In fact the “high” nitrogen fixtures category is a rogues gallery of successful dispersive species, like Russian olive (Eleagnus angustifolia), kudzu (Pueraria lobata), and Scotch broom (Cytisus scoparius). I decided to use the database to generate lists of native and non-native nitrogen fixers and categorize them by their efficiency.

Red alder, a “high” nitrogen-fixing native, coppiced with sea kale in my garden

Though not all native plant enthusiasts would believe it, I’ve spent decades promoting underutilized native plants. While you may choose to grow non-native pears and peaches in your food forest, there is no particular reason to grow a non-native nitrogen fixer over a native one, with all things being equal. In fact I tend to assume that native plants have a network of visible and invisible relationships with other organisms of all kingdoms, making them more desirable to use whenever possible. I think with the information these databases have provided, we are in an excellent position to promote particular native nitrogen fixers for use in permaculture projects.

In many cases there’s a strong temptation to use nitrogen fixing species which are also edible. I’d like to point out that if you harvest a heavy crop from a nitrogen fixer, you’ve probably taken most of the nitrogen with you, though this may not be the case with fruits as much as it is with beans and leaves. This is another good reason to use efficient native nitrogen fixers even if they’re not edible. On the other hand, if what you really need is nitrogen there are very few native species in the “high” category, making a good case for use of white clover and other non-natives.

With that said, let’s look at a few tables I put together for different regions of the country and then review some of our top native candidates. The astute reader will note that there are very, very few natives in the “high” category. I would speculate that there may be few anywhere, but that they are spreading around very, very successfully.

EASTERN FOREST REGION USA

  HIGH NITROGEN MEDIUM NITROGEN LOW NITROGEN
TREES, NATIVE   Robinia pseudoacacia Catalpa speciosa (*), Gladitsia aquatica (*), Gymnocladus dioicus (*)
TREES, NON-NATIVE Alnus glutinosa, Elaeagnus angustifolia Albizia julibrussin  
SHRUBS, NATIVE   Alnus incana, A. maritima, A. serrulata, Amorpha fruticosa, A. glabra, Elaeagnus commutata, Morella pensylvanica (=Myrica), Senna marilandica, Shepherdia argentea, S. canadensis Acacia constricta, Alnus viridis crispa, A. incana rugosa, Ceanothus americanus, Comptonia perigrina, Myrica gale,
SHRUBS, NON-NATIVE Cytisus scoparius Caragana arborescens, Elaeagnus umbellata  
VINES, NATIVE   Apios americana, Lathyrus japonicus, Wisteria frutescens Vicia americana
VINES, NON-NATIVE Pueraria lobata (**) Lathyrus tuberosus, Vicia cracca Vicia sativa
HERBS, NATIVE Dalea candida Amorpha canescens, Dalea formosa, Dryas octopetala, Lespedeza hirta, L. capitata, Hedysarum boreale Astragalus canadensis, Baptisia tinctoria, Dalea purpurea, Desmanthus illinoiensis, Desmodium paniculatum, D. perplexum, D. tortuosum, Glycyrrhiza lepidota,
HERBS, NON-NATIVE Astragalus cicer, Medicago sativa, Trifolium repens Lotus corniculatus, Melilotus indicus, Securigera varia (=Coronilla), Trifolium pratense  

*Reports vary on the ability of this species to fix nitrogen but it is identified as doing so in USDA Plants Database, it may be an error.

**235 kg/ha/yr or 207 pounds/acre. Hickman, Jonathan E., Shiliang Wu, Loretta J. Mickey, and Manuel T. Lerdau. “Kudzu (‘‘Pueraria Montana’’) Invasion Doubles Emissions of Nitric Oxide and Increases Ozone Pollution.” Proceedings of the National Academy of Sciences of the United States of America, Vol. 107.22, 10115-10119, 2010.

COLORADO

  HIGH NITROGEN MEDIUM NITROGEN LOW NITROGEN
TREES, NATIVE      
TREES, NON-NATIVE Elaeagnus angustifolia Robinia pseudoacacia  
SHRUBS, NATIVE   Alnus incana tenuifolia, Amorpha fruticosa, Ceanothus velutinus, Elaeagnus commutata, Shepherdia argentea, S. canadensis Cercocarpus ledifolius, C. montanus,
SHRUBS, NON-NATIVE   Caragana arborescens Purshia stansburiana, P. tridentate, Robinia neomexicana
VINES, NATIVE   Apios americana Vicia americana
VINES, NON-NATIVE     Vicia sativa
HERBS, NATIVE   Amorpha canescens, Dalea formosa, Dryas octopetala, Hedysarum boreale Dalea purpurea, Desmanthus illinoiensis, Glycyrrhiza lepidota, Lupinus argenteus, L. sericeus,
HERBS, NON-NATIVE Astragalus cicer, Medicago sativa, Trifolium hybridum, T. repens Melilotus indicus(=Coronilla), Trifolium pratense  

CALIFORNIA

  HIGH NITROGEN MEDIUM NITROGEN LOW NITROGEN
TREES, NATIVE Alnus rubra  Alnus incana, Alnus incana tenuifolia Morella californica, Olneya tesota, Prosopis pubescens
TREES, NON-NATIVE Elaeagnus angustifolia, Leucaena leucocephala Albizia julibrussin, Robinia pseudoacacia  
SHRUBS, NATIVE   Amorpha fruticosa,  Ceanothus velutinus, Shepherdia argentea, S. canadensis, Alnus rhombifolia, A. viridis sinuata,Ceanothus cordulatus, C. cuneatus, C. fresnensis, C. greggii, C. integerrimus, C. megacarpus, C. papillosus, C. sanguineus, C. ercocarpus ledifolius, C. montanus, Purshia glandulosa, P. stansburiana, P. tridentate, Robinia neomexicana
SHRUBS, NON-NATIVE Acacia cyclops, A. longifolia, A. melanoxylon, Cytisus scoparius Caragana arborescens  
VINES, NATIVE   Lathyrus japonicus, L. littoralis, L. polyphyllus, Vicia americana,
VINES, NON-NATIVE   Vicia cracca  
HERBS, NATIVE   Astragalus agrestis, A. filipes, A. lentigenosus, A. purshii, Lupinus arboreus, L. elmeri, L. nevadensis Trifolium longipes, T. macrocephalum, T. wormskioldii Astragalus Canadensis, A. curvicarpus, Calliandra eriophylla, Ceanothus prostratus, Glycyrrhiza lepidota, Lotus crassifolius, Lupinus argenteus, L. caudatus, L. covillei, L. latifolius
HERBS, NON-NATIVE Astragalus cicer, Medicago sativa, Trifolium hybridum, Trifolium repens Lotus corniculatus, Medicago lupulina, Melilotus offocinalis, Trifolium pratense Caesalpinia gilliesii, Pluchea odorata

I’d like to profile a few of these US native nitrogen fixers that have broad range of applicability.

Red Alder (Alnus rubra) grows throughout much of Western North America, particularly near the coast. It coppices readily, at least if you start when it is young and do it frequently. Unlike most alders it does not require wet feet. It can also handle some partial shade. Here in my garden in Massachusetts is killed the ground during winter and re-sprouts up to 10 feet high the following year. According to the database, this is the only tree native to North America that fixes over 160 pounds of nitrogen per acre per year. Though you might think that other alders are equally powerful, the genus actually shows up in the high, medium, and low categories.

White Prairie Clover (Dalea candida) is a native clover of the prairies that extends some into the Eastern Forest region. It is used to make a tea, but had never crossed my mind as a particularly significantly given at all of the hundreds of species that seemed to grow in the prairie. Now I know that the USDA database states that this is the only herb native to North America that fixes over 160 pounds of nitrogen per acre per year. Though it wants full sun and (and can handle fairly dry soils), I’m going to try to find room for some of this little–used native that is deserving of a place in the spotlight. Interestingly, like alder, members of this genus can be found in the high, medium and low categories.

False indigo is a widely-adapted “medium” native nitrogen fixer.

False Indigo (Amorpha fruticosa) is native to almost the entire country, though it is considered invasive in Connecticut and a noxious weed in Washington. It can be found from flooded riparian areas to extremely dry conditions, though it always wants a good amount of sun. Studies in the Southeast have shown that under their conditions it can be coppiced up to four times a year for alley cropping chop and drop, though permaculturist Jerome Osentowski reports that it does not coppice well in the high desert of Colorado. It is very widely used in China in agroforestry projects due to its fertility benefits and use as a pesticide. I also personally like that it is neither suckering nor thorny. USDA rates this as a “medium” nitrogen fixer.

Buffalo Berry (Shepherdia argentea) it is native from New York through California. It is fairly drought tolerant and suckers extensively. It can produce very high volumes of edible fruit, though you need both male and female plants to get it. It can coppice, though again Jerome Osentowski reports that at his site it does not do so reliably. USDA rates this as a “medium” nitrogen fixer. The related S. canadensis and Elaeagus commutata are also “medium” N-fixers and widely native.

I’d love to hear about your experiments using the database (or this article) to select native nitrogen fixers for your area. Myself, I feel like I have a new tool to make sure that the nitrogen fixers I select will be the best available for the job. I also feel like I can make a strong case for growing some native species that are currently very underutilized.