Lewis and Clark kept detailed notes about the new plants the Corps found in Montana as per President Jefferson' instructions:
"…observations are to be taken with great pains and accuracy; to be entered distinctly and intelligibly… Several copies of these, as well as of your other notes, shoud be made at leisure times, and put into the care of the most trust worthy of your attendants to guard, by multiplying them against the accidental losses to which they will be exposed… "Other objects worthy of notice will be;… The soil and face of the country, its growth and vegetable productions, especially those not of the United States;… the dates at which particular plants put forth, or lose their flower or leaf…"
Though the captains collected dozens of specimens, many did not survive the perils of 19 th Century exploration. River rapids upsetting boats, pack horses spilling cargo, and nearly 3 years of travel with rain, sleet and snow, made it difficult to keep worthy samples of delicate leaves, stems and flowers. The specimens that did accompany the captains to St. Louis and " civilization" were primarily collected on the easterly return trip, as you will see by the collection dates.