"The prevailing wisdom is that it's better to conserve seeds, when possible, than living plants in a glasshouse," says Havens, because living plants can become genetically impoverished due to inbreeding, succumb to disease, or fail to grow in a greenhouse. "In order to build a conservation collection" – as opposed to a display collection – "it's necessary to have big numbers to capture genetic diversity. A couple of oaks from Russia doesn't make for a conservation collection, but 1,500-plus seeds in a bank does."
As the US coordinator for native seed banking, Havens heads a team that will contribute 30 million seeds, including 1,500 kinds of endangered native tall-grass prairie seeds, to the international Millennium Seed Bank Project and to a similar national project, Seeds of Success. She notes that dried, frozen seeds in airtight envelopes can stay viable for 200 years.
Jan Salick, senior curator of ethnobotany at the Missouri Botanical Garden, studies how Tibetan people use high-alpine plants on the eastern edge of the Himalayas, where temperatures are rising quickly. The region is experiencing the fastest glacial retreats in the world and dramatic increases in rainfall. High-alpine meadows, rich in biodiversity, contain rare plants. Dr. Salick's field research shows that as temperatures climb, so do plants – they migrate uphill. The ones migrating fastest are not those endemic to the region, but widespread species that reproduce quickly, outcompeting slower-maturing alpine plants.
The snow lotus, for example, which Tibetans regard as an important medicinal plant, takes 10 years to reproduce and must be pollinated by high-alpine bumblebees. Salick has watched this plant diminish in both size and numbers. "Not until after the fact do you get to see the effect of changes in plant communities on such things as the bumblebees and other long-coevolved, intricate relationships with animal species," she says.
Making 'greener' greenhouses