In Jack and the Beanstalk, seeds tossed out a window spring up overnight, reaching a secret land high above the Earth. In reality, beanstalks, peas, clover, and other plants in the family Fabaceae don’t grow to the clouds, but they come surprisingly close. If you’ve ever planted beans or peas in your garden only to find that they’ve taken over your entire yard, or you’ve tried to remove all the clover from your lawn, you know that Fabaceae are tough plants which can grow in abundance just about anywhere.
The bean plants in the Fabaceae family are perhaps the exact opposite of those in the Orchidaceae, or orchid family. Orchids tend to be very difficult to grow because they have very specific environmental requirements for germination, survival, and propagation. If there is a plant the exact antithesis of Jack’s hearty beansprout, it just might be the elusive and fragile Anacamptis morio, or green-winged orchid. Over the last century this species has lost about 99% of its preferred habitat in England, making it very rare. The orchid is a slender little sprout only about 6 inches tall with a pale green stem and about half a dozen purple flowers, each the size of a grape. When the flowers are pollinated, they can produce tiny seeds no bigger than a speck of dust.
These plants are as particular as they are tiny. In order for one of these green-winged orchids to grow, several barriers must be surmounted. First, one of the very few remaining green-winged orchids must be pollinated and produce the tiny seeds. One of these minuscule seeds then has to blow across the landscape in just the right direction. The wind-borne seed can’t drop into an inhospitable spot – say a river, street, sidewalk, lake, or car – it must land in a garden, and in a spot not covered by other plants. This landing spot must have the perfect amount of daylight and moisture and not too many bacteria (which would decompose the seed). The soil temperature must be just right and the correct species of soil-dwelling beneficial fungi (mycorrhizae) need to be present to trigger the germination process. Finally, the timing has to be just perfect: these growing conditions must be present not just for a day or a single summer but for five whole years! It takes that long for a germinating green-winged orchid seed to mature and bloom into a flowering plant.
If you imagine a place where conditions are perfect for a green-winged orchid to germinate and grow, you might picture a pristine greenhouse with climate controls and near-sterile conditions. But much to the surprise of botanists like me, one of these impossibly particular green-winged orchids was discovered in the most unlikely of places. In central London last May, a staff member at the Household Reuse and Recycling Centre found a single green-winged orchid growing in an unusual location – on the roof.
Now, this isn’t any old roof. The center’s extensive green roof is spread thinly with soil. This special soil doesn’t hold much water and is quite shallow – less than 6 inches deep. (This keeps the green roof lightweight, to prevent structural stress on the building.) This specially-engineered, water-shedding soil isn’t the ideal environment for many plant seeds to germinate or many plant seedlings to grow. In addition to the tricky soil, being up so high means there is no shade, another key challenge for delicate plants.
These harsh environmental conditions mean that many plants struggle to grow on a green roof. And yet, despite the enormous number of barriers and extreme conditions, one incredible green-winged orchid did! This delicate orchid defied surprising odds and is the first of its kind to ever be recorded anywhere in inner London.
For me, the truly magical part of the story is that this little plant’s London home is one example of people in urban spaces embracing nature as something beneficial and valuable. Though tiny, this single orchid and its green-roof home in the middle of London may symbolize a new cityscape, one in which humans start living more harmoniously with other organisms. Perhaps one day it won’t be rare to find orchids and all manner of plants growing on city roofs, creating beautiful sky-high gardens for us to appreciate and enjoy, no magical beanstalk required.