By Kelcie Brown
May 14 2021
When you think of buried treasure, what image comes to mind? Some people may picture gold, gemstones, a wooden chest, and a pirate. There is another type of buried treasure, perhaps more valuable than gold, that is always below us: seeds. Soil seed banks are the always present mixture of seeds in the soil below us, lying dormant until the right conditions allow the plants to grow (Hanson, 2015a). Some may lie dormant for years or even decades, and in some extraordinary cases, such as the “Methuselah” date palm, seeds have germinated after 2000 years of dormancy and remained reproductively viable (Hanson, 2015a).
When you think of buried treasure, there is something else you should picture: a scientist. Specifically, William J. Beal. In 1879, Beal began an experiment that would long outlive him. To study how long farmers would have to weed their fields before exhausting the soil seed bank, Beal buried 20 glass bottles on the campus of Michigan State University, each filled with 50 seeds from 21 common species (Beal, 1905; Hanson 2015a). Two other species were included initially, but buried alongside the bottles in the soil (Beal, 1905). He returned every five years to dig up a bottle, plant the seeds, and see how many would still germinate. 142 years later, the experiment is still ongoing. Now located using a sort of treasure map, bottles are recovered every 20 years, rather than every five. Amazingly, in 2000, 120 years into the experiment, two species did germinate, and they may be species you’d recognize from your own backyard: mullein (Verbascum sp.) and mallow (Malva rotundifolia) (Telewski & Zeevaart, 2002; Hanson, 2015a). The most recent bottle was unearthed in April 2021, and so far eleven seeds have sprouted . The last bottle will not be recovered until 2100.
Germination experiments such as Beal’s are important not only for understanding the amount of work farmers must do to care for the fields, as Beal may have initially intended, but also to preserve the world's plants. The species included in Beal’s experiment are common and considered weedy. Many institutions now have formed large, climate-controlled seed banks to conserve crop species and threatened plants of the world in the face of climate change, war, or natural disaster. Some famous examples are the Svalbard Global Seed Vault and the Kew Millenium Seed Bank.
In herbaria, we preserve dried plant specimens for future research, some of which we may not yet understand or have the tools to discover. Each individual specimen is a permanent record of biodiversity that can tell us about the place a plant was collected, the plant’s evolution, and climatic trends since the time of collection. In seed banks, the purpose is not necessarily to preserve a particular individual, but instead to conserve a species as a whole for future use. Through seed banks, scientists hope to preserve the viability of the seeds for hundreds or even thousands of years by storing seeds under controlled conditions. It is still a living collection, though it lies dormant. Like Beal, scientists at Svalbard and Kew attempt to germinate the seed collections every few years to check viability (Hanson, 2015b). In 2015, the first withdrawal was made from the Svalbard Global Seed Vault. The withdrawn seeds were used to help restore an invaluable agricultural-research gene bank that was destroyed during the Syrian Civil War. This is just one example illustrating the vital work of these scientists and how valuable these seeds are.
Beneath your feet is buried treasure. It could be a weed waiting to sprout, or it could be an ancient palm ready to re-enter the world for the first time in 2000 years. With any luck, and near certainty, the seeds will be here long after we’re gone, and continue to be a treasure for future generations.
