In 1850, a group of influential Scottish and British botanists and horticulturalists organized the Oregon Association to send a handpicked plant collector to bring back plants for the sponsors. They selected John Jeffrey to follow in the footsteps of David Douglas in a search for new botanical treasures.

Jeffrey was born in 1828 at Forneth, Perthshire, Scotland, the eldest son of John and Helen Jeffrey. The family moved to the Kingdom of Fife and in 1841 lived in Lochore, where fifteen-year-old John was a servant at East Blair House a few miles away. In January 1849, the Royal Botanical Garden, Edinburgh, employed young Jeffrey as a gardener. He made a name for himself at the garden and reportedly came to the attention of James McNab (1810-1878), curator of the garden. Energetic and knowledgeable about things botanical, Jeffrey won a prize for the best dried plant collection made near Edinburgh.

Under the auspices of the Hudson's Bay Company, Jeffrey traveled from Scotland to Victoria in British Columbia and then south to San Francisco. He collected plants in Oregon as he traveled between San Francisco and Fort Vancouver, on the Columbia River.

In July and August 1852, Jeffrey collected at least thirteen specimens from the Willamette Valley to the Umpqua River. He collected sixty different species, simply labeled "Oregon Plants 1852-53." He may have collected some of the plants—including California pitcher plant (Darlingtonia californica), California milkwort (Polygala californica), California coffee-berry (Rhamnus californica), and pine violet (Viola lobata)—in the Illinois Valley on his way to the HBC post at Crescent City. Among his best-known collections are Jeffrey pine (Pinus jeffreyi), tall mountain shooting star (Dodecatheon jeffreyi), and foxtail pine (Pinus balfouriana).

Because Jeffrey did not keep a journal of his travels, not much is known about his time in Oregon, and historians know little about the rest of his life. He was last seen in San Francisco in 1854, and then he vanished from the historical record.