Following your lead, I did some reading. Selected excerpts follow:

Pehr Kalm

[Sidebar] A picture commonly believed to portray Kalm, although some modern-day historians have suggested it may be of Kalm’s colleague Pehr Gadd.[1] Painted by Johan Georg Geitel, 1764.

Pehr Kalm (6 March 1716 – 16 November 1779), also known as Peter Kalm, was a Swedish explorer, botanist, naturalist, and agricultural economist. He was one of the most important apostles of Carl Linnaeus.

In 1747, he was commissioned by the Royal Swedish Academy of Sciences to travel to the North American colonies in order to bring back seeds and plants that might be useful to agriculture. Among his many scientific accomplishments, Kalm can be credited with the first description of Niagara Falls written by a trained scientist.[2] In addition, he published the first scientific paper on the North American 17-year periodical cicada, Magicicada septendecim.

Kalm wrote an account of his travels that was translated into numerous European languages; a 20th-century translation remains in print in English as Peter Kalm’s Travels in North America: The English Version of 1770, translated by Swedish-American scholar Adolph B. Benson…

Kalm studied at the Royal Academy of Turku from 1735. In 1740, he entered the University of Uppsala, where he became one of the first students of the renowned naturalist Carl Linnaeus. In Uppsala, Kalm became the superintendent of an experimental plantation owned by his patron, Baron Sten Karl Bielke.[4]…

he was also appointed by Linnaeus and the Royal Swedish Academy of Sciences (of which he had been a member since 1745) to travel to North America to find seeds and plants that might prove useful for agriculture or industry. In particular, they wanted him to bring back the red mulberry in the hope of starting a silk industry in Finland (which was then an integral part of Sweden, today also known as Sweden-Finland.

On his journey from Sweden to Philadelphia, Pennsylvania, Kalm spent six months in England, where he met many of the important botanists of the day. Kalm arrived in Pennsylvania in 1748; there he was befriended by Benjamin Franklin and naturalist John Bartram...

In his Species Plantarum, Linnaeus cites Kalm for 90 species, 60 of them new, including the genus Kalmia, which Linnaeus named after Kalm. Kalmia latifolia (Mountain-laurel) is the state flower of Pennsylvania and Connecticut.
https://en.wikipedia.org/wiki/Pehr_Kalm

A side note: John and son William discovered the subsequently named tree, Franklinia alatamaha.

“No tree which ornaments our gardens has a more romantic history,” begins a lengthy 1933 article published in The Pennsylvania Magazine of History and Biography. The history of Franklinia’s discovery in coastal Georgia, followed by disappearance in the wild, and saved only by its ability to grow, flower, and seed in the Philadelphia garden of its initial collector entail the main thread of the unusual botanical history.[9]
Philadelphia botanists John and William Bartram first observed the tree growing along the Altamaha River near Fort Barrington in the British colony of Georgia in October 1765. John Bartram recorded “severall very curious shrubs” in his journal entry for October 1, 1765. William Bartram returned several times to the sameto the American South, funded by Dr. John Fothergill of London. William Bartram collected F. alatamaha seeds during this extended trip to the South from 1773 through 1776, a journey described in his book Bartram’s Travels published in Philadelphia in 1791. William Bartram brought seed back to Philadelphia in 1777 at which time William reported to his father that he had relocated the plant, but this time had been able to retrieve its seeds although it was not until after John’s death (1777) that he was able to achieve flowering plants (1781). After several years of study, William Bartram assigned the “rare and elegant flowering shrub” to a new genus Franklinia, named in honor of his father’s great friend Benjamin Franklin. The new plant name, Franklinia alatamaha, was first published by a Bartram cousin, Humphry Marshall, in 1785 in his catalogue of North American trees and shrubs entitled Arbustrum Americanum. (Marshall 1785: 48–50; Fry 2001).

Franklinia alatamaha is a small deciduous tree growing to 10 m (33 ft) tall, but commonly 4.5–7.5 m (15–25 ft).[6] It is prized for its fragrant white flowers, similar to single white Camellia blossoms; the smell may remind some of orange blossoms or honeysuckle.[7] The tree has a symmetrical, somewhat pyramidal shape, often with different individuals of the species forming almost identical crowns. It frequently suckers and can form several vertical trunks close to ground level. The bark is gray with vertical white striations and has a ridged texture. The alternate, obovate leaves are up to 6 in (15 cm) in length and turn a bright orange-red in the fall. Although difficult to transplant, once established, F. alatamaha can live a century or more.

The seed capsules require 12–14 months to mature. Unlike almost all angiosperms, Franklinia alatamaha exhibits zygotic dormancy. It pollinates in late summer or early autumn, is then dormant over winter, and only sets fruit during the subsequent summer. Female gametophytes are mature prior to pollination, with double fertilization occurring soon after pollination. The zygote becomes dormant immediately after fertilization with delay of development until the following summer. Initial development of endosperm occurs for up to 3 months after fertilization but comes to a standstill at winter’s onset. With onset of the following summer, embryogenesis begins and endosperm development restarts. This overwinter zygotic dormancy is extremely rare among temperate angiosperms.[8] When ripe the pentavalved spherical capsules split above and below in a unique manner.

The tree was last verified in the wild in 1803 by the English plant collector John Lyon (although there are hints it may have been present into at least the 1840s).[11] The cause of its extinction in the wild is not known, but has been attributed to a number of causes including fire, flood, overcollection by plant collectors, and fungal disease introduced with the cultivation of cotton plants.[12]

All the Franklin trees known to exist today are descended from seed collected by William Bartram and propagated at Bartram’s Garden in Philadelphia. It has now been cultivated in over 1000 sites worldwide including botanical gardens, private homes, parks, and cemeteries.[13][14] It is suggested that more than one tree was sampled by Bartram during his original collection in Georgia and the diversity was maintained over the years.[15] To mark the 300th anniversary of John Bartram’s birth in 1998, Bartram’s Garden launched a project to locate as many Franklinia trees as possible.[14]
https://en.wikipedia.org/wiki/John_Bartram
Botanical drawing below:

(In an atypical show of restraint, I shall not add commentary on the genus Fothergilla, except to note its pleasing form, sweetness of flower, and bright Autumn leaf color.)