Natives for Nutrition and Healing: Green Roof Plants with a Purpose

Advertisement

Well-armed with spines, the prickly pear fruits and pads are edible, highly nutritious, and were a staple of North American indigenous cultures for thousands of years. Fruits and pads can be eaten raw, baked, grilled, and made into jelly, candy, or juiced for liquid refreshment. At least 31 species of Opuntia are native to North America and grow in every state in the U.S., every province in Canada, and many locations across Mexico. A green roof on the offices of Good Earth Building 1 (shown here), is located in San Diego, California, and features Opuntia as part of a green roof display (Dvorak and Drennan 2021). Prickly pear is one of the most adaptable native succulents grown on green roofs in North America, is edible, and requires very little attention. During harvesting events, staff at the Botanical Research Institute of Texas, hull off hundreds of pounds of spineless prickly pear pads from its green roof. Some harvest its fruits and pads to cook them into a jam or jelly! Photo: Bruce Dvorak

Anyone old enough to remember Euell Gibbons will surely recall his cereal commercials from the early 1970s. Euell would blaze a trail in the wilderness and stop to pluck off a plant part—for eating! He would then dine at a table set in the wilderness and eat a crunchy bowl of cereal. The implications were that nature is pure and simple and can be healthy to eat. Such knowledge was required of early American settlers if they were to survive. They learned which plants were appropriate to eat raw, cooked, or boiled.

However, many plants native to North America have a long tenure with humans gathering, seeding, planting, cultivating, and spreading them across the land. Long before the European settlement of North America, Native Americans learned much about the edible indigenous plants and passed this knowledge on to their children for millennia. They learned which plants and plant parts were edible and which were useful for eating, drinking, and healing. In fact, the indigenous cultures significantly influenced the spread of native food plants across many parts of North America including some 1800 taxa (Turner and Aderkas 2012). Maize (Zea mays), for example, is a well-known grain native to Central America, and its many varieties were spread across North America by indigenous peoples. It was often grown intertwined with native beans (Phaseolus vulgaris), and squash (Cucurbita pepo) to form a sustainable form of agriculture known as the “three sisters.” Each plant plays an ecological role in helping the other plants survive and thrive (Kapayou, Herrighty et al. 2022). There are many such plants eaten today that are native to the continent, and many of these are grown on green roofs.

Nearly 5,000 of North America’s 17,000 native plant species offer humans some nutritional or healing value. Unfortunately, nearly 96 per cent of those native plants are now or are considered likely to become endangered! Where better can we begin to teach the next generation about the ethics and values of conservation than through growing tasty and nutritious food from native plants on the rooftops of schools and local businesses? In this issue, I feature green roofs that were designed to help teach the next generation about how plants, including native plants, can be a source of nutrition and healing.

Advertisement

A collection of cheerful natives support pollinator habitat at The Nest’s rooftop garden. Pollinators play an important role in the production of rooftop crops. This diverse planting helps to attract and keep pollinators on the roof. Photo: Bruce Dvorak

“The Nest'' is a rooftop lounge/oasis on the campus of the University of British Columbia in Vancouver, B.C. It includes a sustainable food garden and green roof located on top of the Student Union Building. The project has been run by “Roots on the Roof,” a student-led Alma Mater Society (AMS) club since 2015. Native plants are not the only kind found growing on the rooftop, there are also popular plants from around the world. However, native plants play a primary role. A small patch of native wildflowers (shown above) is situated adjacent to the food crops to provide diversity and attract and keep pollinators on the roof. Native plants such as maize, squash, and berry-producing woodies are also grown and harvested on the roof. Carley Hilbert, President of Roots on the Roof said, “We currently have a row of native blueberries, honeyberries, and a huckleberry bush and we are planning to get a trailing blackberry bush next spring. We also have introduced species growing on the roof such as chickweed, wall lettuce and dandelions which are part of our seed bank, but we consume them nonetheless.”

A bench provides a place to rest from work, but it is also a convenient place to hold some of the many gardening tools used by student volunteers. Specialized waterproofing and protection boards are used beneath the soil to protect and prevent damage to waterproofing systems where digging and cultivation take place. Photo: Bruce Dvorak

Beyond “The Nest”, there are a number of other forms of native plants that can be grown on rooftops. Many of these (native to the Pacific Northwest) also grow in other regions as well. At least thirty-two taxa of berries are edible. Some of these include bearberry, blackberry, blueberry, huckleberry, elderberry, strawberry, raspberry, and oregon grape. Many of these have been grown on semi-intensive or intensive green roofs in North America (Dvorak and Roehr 2021, Dvorak and Rottle 2021).

Three ferns native to North America include edible parts: ostrich fern, Matteucia struthiopteris, lady fern Athyrium filix-femina, and bracken fern Pteridium aquilinum. The new fronds, which are the young tender shoots or “fiddleheads”, are edible and can be steamed, boiled, or canned. The mature fronds, however, are not edible and could make you sick. For this reason, some expert guidance is necessary for those looking to expand their palette with ferns.

For those who favor the savory supplement of mushrooms to their diet, there are at least thirty Fungi that are edible, and native to the Pacific Northwest. Of course, expertise in identification is critical for the success of collecting wild mushrooms. Intentionally grown on rooftops, mushrooms are not as well-known but sometimes they make an unexpected appearance. And for the more adventurous, many native lichens and mosses are edible but may not be very tasty.

North America has a variety of popular edible native plants that may grow on green roofs. In addition to native berries and fruits, varieties of other popular native annuals include varieties of squash, pumpkin, onion, tomato, pepper, bean, potato (South America) and more. Many universities support agricultural extension services and may offer local guidance regarding which native plants may be grown for consumption and where they grow.

Advertisement

This image of a working garden at the grounds of the Seattle Children’s PlayGarden includes sunflowers (shown here) and grows on rooftops. Sunflowers are native to North America and were an important part of the diet of indigenous peoples. The Garden House building sports a sedum-based green roof. Photo: Bruce Dvorak

Beyond those mentioned familiar native plants, some of the most popular plants on green roofs are also edible. Some species of Stonecrop (i.e. Sedum) are edible. Its new leaves and shoots are edible raw; however, older plants should be avoided, as they may taste bitter. The rhizomes can be boiled and then eaten. Sedum lanceolatum and Sedum divergens are both native to western regions of North America and are edible. Another popular plant on green roofs in the Pacific Northwest is Camas, both Great camas (Camassia leichtlinii) and Common camas (Camassia quamash). Although the bulbs can be boiled, most people prefer bulbs slow-cooked and dried. Before one runs out into the wild places to begin hunting for raw Camas bulbs to eat (check local regulations), it should be known that similar-looking plants, with white bulbs, could be mistaken for camas but are poisonous. Death Camas (Zigadenus elegans) and Meadow Death-Camas (Zigadenus venenosus) can sometimes appear to look similar to camas. Other edible native plants also adapted to green roofs include wild onions (Allium schoenoprasum), also known as chives, and also annual sunflowers (Helianthus annuus) are native to North America.

Green roofs with wet habitats could support wapato (Sagittaria cuneata) which was important for indigenous cultures for treating headaches, indigestion, and many other ailments.

Oddly then, the extensive green roof (not visible here) on the rooftop of the Garden House building at the Seattle PlayGarden, has a sedum roof and might be considered edible for some people, but it was not designed or encouraged to be. However, the ground scape has lush edible gardens which includes an old pickup truck that now grows crops where its bed once carried its payload, and instead of burning petroleum it now consumes solar energy and produces edibles. Projects like this, introduce to children an early and enjoyable affiliation for plants, and engage all with fun activities that support diversity of life, and edible natives.

This garden was designed for children with disabilities, is ADA accessible, and is planted with hundreds of plants that have edible parts. This garden was designed by Wendy Welch (Wendy Welch Garden Design) and landscape architect Daniel Winterbottom, a professor at the University of Washington.

An old truck makes for some fun play for children at the Seattle Children’s PlayGarden. Edibles grow above the ground in the elevated planters made from the void spaces of this salvaged truck. Kids can climb inside to play, or reach up into the planters to weed, plant or help harvest food. Photo: Bruce Dvorak

Schools are one way to educate the next generation about how green roofs and native plants can support urban agriculture. Connecting with the public at large is another opportunity. While scale of application is a critical issue for those looking to support or supplement income from rooftop agriculture, there are some that look to diversify application and operations of food crops and educate the public as part of its experience. Grow + Gather is a for-profit business located in Englewood, a suburb of Denver. With Denverites growing in sophistication and knowledge of green roofs with its green roof bylaw, entrepreneur Jeff Johnston tapped into this market by transforming an old gas service station into a coffee shop, restaurant and event space that include planted rooftop and indoor growing of produce. Popular menu items include tomatoes, peppers, herbs grown on a rooftop greenhouse and other nearby sites. Inside the former garage bay (where autos were serviced) grow lights and hydroponics grow lettuce and herbs. The rooftop over the coffee shop is covered with a dense planting of perennials and annuals native to the shortgrass prairies. The restaurant, event space and coffee shop include informative signs and menus that inform visitors about the values of healthy food, local food and the types of plants grown on site, on the rooftop and adjacent gardens.

Advertisement

While Brooklyn Grange, and similar sized operations demonstrate large scale applications of rooftop agriculture, establishments such as Grow + Gather demonstrate how smaller scale applications can function to serve, nourish and educate local neighborhoods about conservation and nutrition and healing values of native plants. The native wildflowers, grasses and bulbs shown here grow above the coffee shop. They are not intended for eating, however, they support pollinators that may visit the rooftop or the crops growing at the ground level behind the coffee shop. Green roof by Green Roofs of Colorado. Photo: Bruce Dvorak

Summary

One way to help educate the next generation to develop values for the immense resources that are found in native plants is to include green roofs, with native plants on K-12 schools, universities as well as local businesses. This includes growing native plants that can be consumed for nutrition or healing. The projects featured here represent just a few of the many buildings and businesses across North America, where native plants are already included as part of the learning environment.

There is gaining momentum to require green roofs on schools. With such proposals realized, perhaps the next generation will become inspired to embrace and place a greater value for nature, including learning about edible native plants. Edible native plants can be part of schools and local businesses and help enrich the lives of those who encounter them, especially on rooftops.

Many forms of plants native to North America offer edible sources of nutrition and healing. These include annual herbs, shrubs, ferns, bulbs, succulents, vines, and perennials. Plant parts include leaves, berries, seeds, nuts, flowers, shoots, and roots.
Some forms of plants commonly grown on green roofs such as sedum, may be edible. Perhaps exploration of how such plants can be used is necessary as very little is published regarding how sedums can be used as an enjoyable source of nutrition or healing.
Local expertise and sourcing of plants is critical. Edible rooftop gardens should not be designed, installed or maintained without the support and approval and requirements of local authorities.
Specialized design and maintenance practices are needed to establish, care for and sustain rooftop agriculture. Local experts should be consulted to be certain that codes, regulations and rooftop construction proposals are durable and sustainable.
Including students and volunteers with the maintenance of rooftop agriculture is a great way to grow knowledge of this emerging field.
Interpretive signage, links to websites via QR codes, docent tours or other forms of outlets may be necessary to grow knowledge and the values of edible plants for rooftops.

Advertisement

Bruce Dvorak, FASLA is an Associate Professor at Texas A&M University in the Department of Landscape Architecture and Urban Planning, where he has been conducting green roof and living wall research since 2009. Bruce is a member of the GRHC Research Committee and founded a new Regional Academic Center of Excellence in 2022, the Southern Plains Living Architecture Center. Bruce received the GRHC Research Award of Excellence in 2017 and teaches green roofs and living walls in his courses in landscape architecture programs at Texas A&M University. His edited book, Ecoregional Green Roofs: Theory and Application in the Western USA and Canada (2021) provided inspiration and content for this article.

Acknowledgements

I would like to thank Carly Hilbert, President of Roots on the Roof, at the University of British Columbia for details regarding The Nest roof garden. I would also like to thank Jeff Johston and Dr. Jennifer Bousselot for arranging a visit, tour, and a delicious meal at Green + Grow. Thank you to Dr. Brooke Byerly Best with the Botanical Research Institute of Texas for details regarding cactus harvesting events, and to Jim Mumford founder of Good Earth Plants for a tour of its green roof.