What Plants Did Lewis and Clark Discover?

Lewis and Clark’s expedition is commonly credited with 178 plants, shrubs, trees, and herbs not previously recorded for science; familiar plants connected with its collections include purple coneflower, bitterroot, Lewis’ mock orange, Lewis’ monkeyflower, blue flax, pink fairy, black cottonwood, and ponderosa pine. But “discovered” needs careful reading: some expedition records were later identified from specimens or descriptions. The most reliable way to use a plant list is to distinguish a documented collection from a plant formally recognized as new to science.

What “Discovered” Means in Lewis and Clark Plant Lists

The Corps of Discovery traveled through plant communities that had not been closely documented by Euro-American science. President Thomas Jefferson specifically asked the expedition to observe the natural world, and Meriwether Lewis prepared for that work by studying with scientists in Philadelphia.

As they traveled, expedition members recorded habitats, flowering times, growth forms, and possible uses. They pressed plant specimens and protected them from rain and river water in oilcloth. Back in the East, botanists could compare those collections with known plants and publish formal scientific names.

That process creates three different meanings of “discovered”:

First recorded for science: The expedition made the first known scientific record of a species.
Collected or described by the expedition: The plant was documented in a journal or preserved as a specimen, even if it had already been known to science.
Named in honor of Lewis or Clark: A plant’s scientific name honors an expedition leader without indicating the expedition was the first to find it.

Those categories overlap sometimes, but they are not interchangeable.

A Selected List of Plants Associated With the Expedition

The following table is a practical, representative list, not a claim that every plant named here was completely unknown to all earlier botanists. Common names can also vary by region, and botanical classifications are updated over time.

Plant	Common Scientific Name	Why It Is Associated With Lewis and Clark
Purple coneflower	Echinacea species	The National Park Service identifies purple coneflower as a species first recorded for science by the expedition.
Bitterroot	Lewisia rediviva	A plant associated with the expedition.
Lewis’ mock orange	Philadelphus lewisii	A plant associated with the expedition.
Lewis’ monkeyflower	Erythranthe lewisii	A plant associated with the expedition.
Blue flax	Linum lewisii	A plant associated with the expedition.
Pink fairy	Clarkia pulchella	A plant associated with the expedition.
Black cottonwood	Populus trichocarpa	A tree documented by the expedition.
Ponderosa pine	Pinus ponderosa	A plant associated with the expedition.

Purple coneflower is especially useful in a short answer because it has a direct connection to the expedition’s scientific record. The National Park Service groups it with the black-billed magpie as one of the species first recorded for science by the Corps of Discovery.

Other widely repeated “Lewis and Clark plant” lists may include additional grasses, sages, shrubs, prairie flowers, and trees. Some entries are based on a surviving specimen, a journal description, or a later historical interpretation.

How to Check Whether a Plant Belongs on a Lewis and Clark Discovery List

A careful check prevents a plant from being labeled a “discovery” when the evidence only shows that the expedition mentioned it.

Step 1: Identify the Claim Being Made

Start by asking what the list actually means by “discovered.”

Look for wording that makes clear what kind of connection is being claimed.
Keep each type of claim separate.
Avoid assuming that a plant named lewisii or clarkii was necessarily first encountered by the Corps of Discovery.

Step 2: Look for a Voucher Specimen or Journal Entry

A botanical voucher is a preserved specimen used to support a plant identification. It is stronger evidence than a later retelling because botanists can examine the physical plant, compare it with modern material, and revise the name if taxonomy changes.

When reviewing a historical plant claim:

Check whether the entry has a collection date and location.
Look for a voucher number or herbarium record.
Compare the historical description with the current plant name.
Record uncertainty instead of forcing a modern name onto a vague entry.

The expedition’s notes matter even when a specimen is missing. Lewis often described features such as habitat, leaves, flower color, scent, or local use, and those details can help historians propose an identification.

Step 3: Use Careful Language for Uncertain Entries

Finish your notes or plant label with language that matches the evidence:

“First recorded for science by the expedition”
“Collected by the expedition”
“Mentioned in Lewis’s journal”
“Historically identified as”
“Unidentified botanical voucher”

Unidentified botanical vouchers remain an important part of the historical record.

Why Some Expedition Plants Cannot Be Named With Confidence

A collection record and a confirmed scientific identification are not the same thing.

The Lewis and Clark herbarium is impressive, but it is not complete. The first thirty botanical entries are missing from the Academy collection, so researchers must rely on Lewis’s written descriptions to identify them.

There are also voucher numbers that remain unresolved. Numbers 37, 62, and 102 are still unidentified.

Many popular lists combine several levels of evidence.

The University of Nebraska’s Journals of the Lewis and Clark Expedition maintains botanical identification material that helps show why this distinction is necessary.

Indigenous Knowledge Came Before the Expedition

The expedition encountered plants in homelands where Native nations had long understood their food, medicinal, material, seasonal, and cultural uses. A plant could be “new to science” in the narrow sense that it had not been formally recorded for science.

That distinction is especially important for gardeners and growers. Plant knowledge is not limited to Latin names or herbarium sheets. Knowledge of where a plant grows, when it flowers, which animals use it, whether it is edible, and how it responds to fire, drought, or flooding is also botanical knowledge.

Lewis and Clark’s journals sometimes recorded Indigenous names and uses.

When Lewis and Clark’s Plant Findings Became Public

The expedition returned in 1806, but its findings did not become widely available right away. The official expedition journals and Clark’s map were not published until 1814, eight years after the journey.

That delay helps explain why later botanists played such a large role in naming and organizing the plants connected to the expedition. Lewis had collected material and made observations, but the work of formal publication, comparison, and classification continued after the expedition ended.

For anyone researching a garden plant with a Lewis or Clark connection, the useful next step is to separate these dates:

The date the expedition saw or collected the plant.
The date a specimen was preserved or cataloged.
The date the plant received a formal scientific name.
The date the information was published for other scientists to examine.

Frequently Asked Questions

How many plants did Lewis and Clark discover?

Lewis and Clark’s expedition is commonly credited with 178 plants, shrubs, trees, and herbs not previously recorded for science. That number is best treated as a historical summary, not as a guarantee that every item has an intact specimen and universally settled modern identification.

What was the most important plant Lewis and Clark discovered?

There is no single official “most important” plant, because importance depends on whether you mean scientific history, ecology, garden value, or cultural use. Purple coneflower is a strong documented example because the National Park Service identifies it as first recorded for science by the expedition.

Did Lewis and Clark discover Douglas-fir?

Douglas-fir is often included in popular accounts of the expedition’s western plant observations, but “discovered” can be misleading. It is better to say that Lewis and Clark documented western conifer landscapes than to treat every prominent tree they saw as a first scientific discovery.

Which plants were named after Lewis and Clark?

Plants associated with the expedition include bitterroot, Lewis’ mock orange, Lewis’ monkeyflower, and blue flax. Pink fairy, Clarkia pulchella, is another plant associated with the expedition. An honorific name shows that a botanist wished to recognize Lewis or Clark; it does not automatically establish who first found the plant.

Why are some Lewis and Clark plant records unidentified?

Some original specimens have been lost, damaged, or were never accessioned into the surviving herbarium. The first thirty entries are missing from the Academy collection, and voucher numbers 37, 62, and 102 remain unidentified. If you are tracing a particular plant claim, start with the expedition’s journal entry and botanical voucher record rather than relying only on a modern list.