By the beginning of October 1918, the influenza pandemic was racing through Boston. Businesses had been shuttered. Schools had been closed. A local conference for the National Association of Gardeners was postponed. Meanwhile, at the Arnold Arboretum, director Charles Sprague Sargent was finding it increasingly difficult to navigate a quarantine of a different nature—one designed to prevent horticulturists from inadvertently introducing pests and diseases on imported plants. Arboretum plant collector Ernest Henry Wilson was nearing the end of a two-year expedition to Japan, Korea, and Taiwan, and Sargent was especially concerned that an unusual conifer that Wilson had collected in Taiwan, aptly named Taiwania cryptomerioides, would not survive the inspection process in Washington, DC. “Delays in Washington are, as you know, often fatal,” Sargent wrote to an official at the United States Department of Agriculture, in a letter dated October 11, 1918.

Wilson returned to Boston the following March, about a month before the Taiwania. The plants evidently received no special accommodations to forego the inspection, given that other plants from Wilson’s expedition would arrive at the same time, including the spike winterhazel (Corylopsis spicata, accession 10544) and the buttercup winterhazel (C. pauciflora, accession 10156). While Sargent knew the Taiwania wouldn’t be hardy enough to live outside the Arboretum greenhouses, the winterhazels would eventually find a home in the back corner of the hickory collection, where they are now among the earliest plants to bloom. The flowers of both species are produced in drooping clusters that are a delicate shade of yellow, like lemon chiffon cake, with translucent bracts that catch the sunlight. The buttercup winterhazel is slender and intricately textured, while the other species is coarser but still subtle and refined.

Shortly after these plants arrived from Wilson’s expedition, a new plant quarantine, debated in Washington amid the influenza epidemic, would be implemented, effective June 1919. In the annual report of the Arboretum for the following year, Sargent would lament the quarantine, claiming that the Arboretum had “given up” importing plants. While it is clear, based on the Arboretum plant records, that plants continued to arrive at the Arboretum from abroad—including a significant shipment from China, sent by Joseph Hers, a Belgian railroad engineer—the inspection process in Washington proved onerous. “The methods of disinfection adopted by the Federal Board are so crude and so unnecessarily severe that a large proportion of the plants and seeds subjected to them are killed,” Sargent wrote in the report. A remarkable Hubei wingnut (Pterocarya huphensis, accession 15390*B) from Hers now stands beside Wilson’s winterhazels, the spring buds still waiting to expand, forming a curious collection of plants from the early era of plant quarantines.

Yellow flowers of winterhazel showing no leaves on branch
Expanding flower buds of buttercup winterhazel (Corylopsis pauciflora, 10156*D). Jonathan Damery

Sargent would ultimately concede to the new inspection protocol, however, and according to his biography, the octogenarian director would occasionally travel to Washington to ensure that the process went smoothly for major Arboretum collections. Today, seeds from the Arboretum’s international expeditions predominantly undergo inspection at JFK International Airport, in Queens, New York. The importance of these inspections is underscored by the periodic discoveries of new plant diseases and pests in the United States. For instance, in 1996, the Asian long-horned beetle (Anoplophora glabripennis) was first documented in the United States, in New York, and it has since spread throughout eastern North America, causing cities like Worcester, Massachusetts, to remove tens of thousands of trees. Emerald ash borer (Agrilus planipennis) was first documented, in Michigan, six years later and has caused similar widespread devastation. But it’s easy to imagine an alternate version of reality, one with no inspections and one where these devastating introductions had occurred with unabated speed and frequency. To borrow a phrase from the current COVID-19 pandemic, the early plant quarantines that frustrated Sargent could certainly be credited with “flattening the curve,” slowing the impact and spread of new plant pests and diseases. Without that flattening, the Arboretum collections—let alone our forests and cityscapes—would certainly be unrecognizable today.

Now, amid COVID-19, Arboretum staff have shifted to work-from-home arrangements, with a slim crew of horticulture staff maintaining the greenhouses and monitoring the new plantings. The pandemic of 1918 echoes loudly in Boston. Schools are once again closed. So, too, are most other businesses. But the Arboretum landscape has been thrumming with visitors. In this new era of home quarantine, free outdoor spaces like the Arboretum have become increasingly essential for anyone who is eager for somewhere to stretch and move, eager for somewhere to watch as spring—including the soft glow of Wilson’s winterhazels—progresses with unabated promise. We do not know what the coming month will hold. So, for now, we water new plants, and we wait for the green flush.