The Palm House at London’s Kew Gardens, completed in 1848, looks like a steamship plowing through a sea of green. The metaphor is apt because the explorers of that era would compete by sailing home from foreign travels with the most bizarre species they could find and bringing them to Kew. One highlight, for example, is the Madagascan suicide palm, which flowers once in 50 years then promptly expires. The Palm House’s oldest plant, an Encephalartos altensteinii palm, was picked up in the 1770s during Captain Cook’s second circumnavigation.

It’s not that the Palm House architects were trying to conjure nautical imagery. But as no one had built a greenhouse of its size before, draftsmen looked for stability in ship design, with its stress-absorbing lines and spilling tiers. In a ...