In August 1895 and September 1896, the dendrologist John George Jack visited his hometown of Chateauguay, on the shores of the St. Lawrence River, near Montreal. By then, Jack had been working at the Arnold Arboretum for a decade. Director Charles Sprague Sargent had hired Jack as a manual laborer in 1886. The self-educated Jack rose over time to become a popular lecturer, a prolific plant collector, and an associate professor of dendrology at Harvard.

Jack returned to Boston from Chateauguay with seedlings of the eastern cottonwood (Populus deltoides). Fifteen members of accession 16611 were planted out near Peters Hill. In 1894, Jack had written a five-part series about the trees and shrubs growing near Montreal in the magazine Garden and Forest, which Sargent oversaw. In the final section, Jack described an impressive cottonwood growing near the Chateauguay River: “This tree is said to have been not much more than a sapling within the memory of some of the older inhabitants.” Already, in 1894, its trunk measured more than five feet in diameter. This remarkable tree bore only pollen-producing male flowers (cottonwoods are dioecious), but the seedlings Jack collected may well have come from nearby. The seed capsules ripen in early summer and burst to release tiny seeds attached to cotton-like strands—nature’s dust bunnies. A single tree can produce up to forty million seeds.

According to the Arboretum’s records, Jack made plant collections near Chateauguay on a near-annual basis through 1912 (the year his mother, Annie, a well-known horticultural writer, died). Cottonwoods were a repeat interest. Another singular tree grew on an island in the mouth of the Chateauguay River, where a convent was then located. Jack had collected an herbarium specimen from this tree in 1889, and he would collect additional specimens from the same tree on at least four other occasions. The undersides of the leaves were more silvery than those of other cottonwoods, and Sargent came to recognize the tree as a hybrid between the eastern cottonwood and the balsam poplar (Populus balsamifera). In 1913, he named the hybrid in Jack’s honor: P. × jackii.

Although Jack collected cuttings from the hybrid, none of the resulting trees are living today. As for the original accession of eastern cottonwoods, five remain, all at the juncture of the Peters Hill loop and the short oak-lined spur leading to Poplar Gate. These are large trees. Their silvery gray bark has matured into deep furrows. The trunk diameter of the largest is around three feet, which is impressive but not nearly the five-foot specimen that Jack had observed towering over the rich bottomlands.

In 1950, a year after Jack died at his farm in Walpole, Massachusetts, his name would appear in the New Yorker, in an essay by Vladimir Nabokov. (The essay was later adapted as the final chapter of Nabokov’s memoir, Speak, Memory.) “I would like to have the ability Professor Jack, of Harvard and the Arnold Arboretum, told his students he had—of identifying twigs with his eyes shut, merely from the sound of their swish through the air,” Nabokov wrote.

Citation: Wheeler, E. 2020. Speak, cottonwoods. Arnoldia, 78(1): 52–53

Nabokov had settled in the Boston area in 1941. Although he was an academic with a literature degree from Cambridge, England, he had, from boyhood on, a deep love of nature—especially butterflies. (He even worked with the lepidopteran collections at Harvard’s Museum of Comparative Zoology.) Whether Jack and Nabokov met is unknown. Yet the writer spelled out examples of trees Jack’s auditory keenness could identify: “hornbeam, honeysuckle, Lombardy poplar.”

Leaves of the eastern cottonwood, like those of the Lombardy poplar (Populus nigra), have flattened petioles. Even the faintest breeze can cause the leaves to rustle. To some, the leaves of the eastern cottonwood shiver. If it’s true that Jack could identify plants by their sound, perhaps, in the case of poplar, he was remembering the sound of wind caressing the big leaves of a mature cottonwood grove along the Saint Lawrence River—perhaps remembering the trees that drew him back again and again.

Emily Wheeler lives in Jamaica Plain and is a docent at the Arboretum.