One hundred percent of our food comes from plants, either directly or indirectly. Plants take sunlight and convert it into a form of energy that animals, such as us, can eat.
Disturbingly though, 90% of our food comes from just 15 crop plants, such as rice and wheat. It sounds like a worrying concentration of eggs in one basket, but there are untold other edible plants, some in disguise.
Dunedin Botanic Garden is full of potential edibles. Grown primarily for their ornamental value, their beauty is what we normally celebrate, but they have an extra edge — they’re pretty plus they’re food.
A new edible plants trail highlights 28 of these plants, across a selection of locations throughout the botanic garden.
Although it’s tempting to taste them, plants in a botanic garden are the same as a museum exhibit and need to be left untouched for others to enjoy.
Berries easily come to mind when we think of edibles. One of the trail’s most delicious berries is Chilean guava, Ugni molinae. It might be better named candyfloss plant, as on a sunny autumn day the berries’ perfume smells and tastes like a fruit-tinged candyfloss. Its small berries are fun for little fingers to reach in and pick.
Small fruit are popularly called a berry but a berry is just one type of fruit. Berries have three layers: the skin, middle and inner layers. The thin inner layer is a defining feature, along with their fleshy body. This science of categorisation has rules and exceptions, resulting in the bizarre fact that bananas are berries but raspberries are not; they’re an aggregate fruit. When it comes down to it though, it’s the taste that counts.
So why are bananas a berry? Because their inner layer is definingly thin. It’s really a membrane that’s been bred to become unobtrusive for human preference.
The bananas we’re so familiar with are a world away from wild bananas and their large seeds. Bananas were one of the earliest plants to be domesticated by humans — one of the modern banana’s parent species, Musa acuminata, was first intentionally cultivated around 8000 BCE.
It was only in the 1800s that what we now know as the banana spread from China to become the dominant product it is today. About 99% of the world’s dessert bananas come from this Cavendish cultivar, meaning we’re relying on a monoculture.
In Ghana, plantain use is further refined into the green one and the ripe one. The ripe one is made into a sweet, spicy, fried snack — kelewele. The green one is healthier and cooked as a stew with vegetables such as spinach and eggplant with a savoury gravy. Peanuts, ginger and other spices are key.
An example of the difference between edible and ornamental is that not all banana species produce edible parts and some are grown just for their vivid flowers.
Bananas grown at the garden are the edible type, kept warm and frost-free in the winter garden glasshouse.
Coffee is growing in the glasshouse too. To create the drink, the ripe, red fruit is removed from the berry, leaving the central seed, which is then dried. Legend has it that a tired Arabian shepherd found his goats acting hyperactively after eating the berries, so tried them for himself. Soon he was addicted to caffeine, leading to the world’s love of coffee.
If you’d like sugar with that you’ll still need a glasshouse and there’s a specimen to see in the winter garden.
Curry’s there too; its leaves are the raw ingredient but they don’t taste like curry when raw. For pudding, you could grow guava, viewable near the goldfish.
Outside in the herb garden are standard kitchen staples, but there’s also chamomile for tea and liquorice for lollies. Liquorice roots contain the natural sweetener glycyrrhizin which is 50 times sweeter than sugar. It grows well in sunny parts of Dunedin.
A contemporaneous expedition, led by Portuguese man Ferdinand Magellan, resulted in the first circumnavigation of the globe, but at the cost of the lives of 242 sailors from an original 260. The cloves the remaining 18 sailors brought home netted them a profit of 2500%. Our modern easy access to spices is quite a feat.
Elsewhere in the lower botanic garden are more edibles in disguise. The herbaceous borders by the main gates are best known for their flowery summer vibrance, but even they contain an edible or two. There’s an ornamental artichoke that is, like the globe artichoke, edible, but this one isn’t pleasant to the taste. Unopened flower heads and stalks can also be eaten — in theory.
Another artichoke species, the Jerusalem artichoke from North America, grows in the upper botanic garden, behind the concrete seat on the friendship lawn. Its root tubers can be cooked and used as a root vegetable similar to potatoes. It’s easily grown in most soil types but doesn’t tolerate salt spray.
Climate, especially warmth, determines whether plants can grow in a foreign land. The upper botanic garden is warmer and has milder frosts than on the flat. Microclimates allow experimentation but, even so, it’s difficult to grow anything too tropical. Three olive trees are growing on the Mediterranean garden’s sunny slope since 2010 and produce tiny edible olives. In the geographic plant collection there’s even an Australian macadamia tree that produces edible nuts every 18 months.
Native plants seem well adapted to local conditions, but some are from warmer northern parts of the country and don’t have southern fortitude. Sometimes their fleshy leafiness gives them away. Kawakawa is a pale, sensitive northerner that can grow here under the shelter of other trees but would stick out in our bush like a fleshy human tongue. Its leaves can be added to boiling water to create a bitter tea that is good for the digestive system and it has sweet orange berries.
One of the more uncanny edibles is Rhododendron arboreum. Here we know it as a large-leaved ornamental valued for its bright red flowers which , in its native India, are cooked and eaten. The Rhododendron Dell also hosts Gaultheria procumbens which, when dried, produces a minty extract to flavour lollies.
To take self-sufficiency to a festive end, the home gardener could consider growing plants to make alcoholic beverages. American aloe, Agave americana, is a succulent usually celebrated here for its strong, simple, large leaves. In New Zealand it can become weedy, but the leaves can be fermented to make an alcoholic beverage called mescal. To make this, the leaves are roasted, pounded, drained then distilled. The Agave genus also provides Agave tequilana, which is used to make tequila.
Humans are omnivores, so are designed to eat plants and we’ve been cultivating them for about 10,000 years. Also, in the 1500s the first European botanic gardens were established for the academic study of medicinal plants, so it may seem strange that botanic gardens now focus on ornamental plants.
It might be hard to imagine a vegetable garden in our city’s botanic garden but, on the other hand, why not? In recent times, edible gardens have sprouted in botanic gardens throughout the world. There’s a growing desire to live off the land sustainably and these gardens are re-educating people in the gardening skills our predecessors considered essential. In response to this desire, Dunedin Botanic Garden plans to establish a demonstration garden. Until then, visitors can explore the edible plants trail and find inspiration on what to plant in their home garden.
Copies of the trail brochure are available from the information centre, which is open daily from 10am to 4pm.
