Lewis and Clark Were Accidentally Building America's First Herbal Medicine Database

Ask most Americans what Lewis and Clark were doing between 1804 and 1806, and you'll get some version of the same answer: mapping the West, looking for a route to the Pacific, meeting Native tribes along the way. All of that is true. But tucked inside the famous journals of the Corps of Discovery is a subplot that history class almost never mentions — one that turns out to be surprisingly relevant to modern medicine.

Meriwether Lewis was, among other things, an obsessive botanical note-taker. And the plant remedies he documented, learned directly from Native American healers and guides, quietly made their way into early American medical practice before largely vanishing from the mainstream. The journals weren't just a travel log. They were, accidentally, one of the most detailed records of Indigenous herbal medicine ever assembled by an outsider.

The Doctor Who Sent Lewis to School

Before the expedition launched, President Jefferson arranged for Lewis to receive a crash course in medicine from Benjamin Rush, one of the most prominent physicians in the young United States. Rush gave Lewis a list of questions to ask Native peoples about their health practices and loaded him up with supplies — including the legendary "Rush's Pills," a purgative so aggressive that historians have since tracked the Corps' campsites by the mercury content in the soil.

But Lewis went well beyond Rush's checklist. He recorded plants with a naturalist's precision: their appearance, their habitat, how they were prepared, and what conditions they were used to treat. By the time the expedition returned, he had documented well over 200 plant species, a significant number of which came with detailed notes on their medicinal applications as practiced by the tribes the Corps encountered.

Three Plants Worth Knowing About

One of the more striking entries involves Osmorhiza longistylis, commonly called smoother sweet cicely — a plant Lewis noted being used by several tribes as a treatment for sore throats, fevers, and digestive complaints. It was applied as a root tea, and Lewis described its smell as similar to anise. Modern phytochemical research has since confirmed that the plant contains compounds with genuine antimicrobial properties. It wasn't magic. It was chemistry that Indigenous healers had worked out empirically over generations.

Then there's Lomatium dissectum, a member of the carrot family that Lewis encountered in the Columbia Plateau region. Native groups used it extensively for respiratory illness, and some historians believe it was used during the 1918 influenza pandemic by communities in the Northwest with notably lower mortality rates. Researchers in the late twentieth century began investigating Lomatium seriously, and several studies have pointed to antiviral activity in its root compounds. It's now sold as an herbal supplement, though most people buying it have no idea it passed through Lewis's notebook first.

Perhaps most poignant is Ceanothus americanus, known as red root or New Jersey tea. Lewis documented its use as an astringent and noted its popularity among multiple tribes for treating respiratory and lymphatic issues. Early American physicians actually picked this one up — it appeared in the U.S. Pharmacopeia in the 1800s before quietly dropping out of official medical literature. Today, herbalists still use it, and preliminary research has looked at its potential effects on lymphatic circulation. It made it into the system, briefly, and then got forgotten.

Why Did It Disappear?

The short answer is that American medicine professionalized rapidly in the nineteenth century, and in doing so, it drew a hard line between "scientific" treatment and "folk" remedy. Indigenous plant knowledge landed firmly on the wrong side of that line — not because it failed to work, but because it came from the wrong people and didn't fit the emerging framework of pharmaceutical standardization.

Lewis's botanical records were studied by physicians like Benjamin Smith Barton, who was supposed to help publish the findings but died before completing the work. The medical dimensions of the journals never received the same attention as the geographic ones. Explorers became heroes. Their notebooks became artifacts. And the plant knowledge inside them got filed away.

A Pharmacopoeia in Plain Sight

What makes this story genuinely interesting today isn't just the historical irony — it's the fact that the journals are sitting in archives, fully accessible, and researchers are still finding things worth following up on. Ethnobotanists have been revisiting the Lewis and Clark plant records for decades, cross-referencing them with modern phytochemistry databases and finding overlaps that are hard to dismiss as coincidence.

The Corps of Discovery wasn't sent west to do medical research. Lewis wasn't a trained botanist or physician. And yet, by paying attention and writing things down, he assembled something that early American medicine briefly touched and then let go — a record of what people on this continent had learned about healing, accumulated over centuries, offered up to outsiders who weren't quite ready to take it seriously.

The journals are still there. The plants are still growing. The chemistry hasn't changed. It's less a forgotten discovery than a discovery that keeps getting rediscovered — and then, somehow, forgotten again.