The total number of specimens he collected is not known, but it is certain that all those he acquired between Fort Mandan and the Great Falls of the Missouri were destroyed when high water in the spring of 1806 flooded the underground cache where they had been stored. Some more went astray after the expedition was over; others were eventually destroyed by beetles. For many years the collection was scattered and generally ignored. Not until 1896 were most of the known sheets assembled in one collection at the Academy of Natural Sciences in Philadelphia, and not until 1966 was it subjected to a comprehensive, detailed study.1
Also, we don't know precisely what methods or materials Lewis used to preserve plant specimens. He might have used presses such as the one pictured here on the previous page, or else books of blotting paper and blank sheets. We do know that all the existing specimens have been remounted at some time in the past two hundred years, and that of the 226 botanical sheets now in the Lewis and Clark Herbarium at the Academy (at http://www.acnatsci.org/research/biodiv/lewis&clark/) only 34 have their original labels in Lewis's handwriting.
The process of pressing specimens preserves only the outlines, textures and skeletal structures of plants, so Lewis also took pains to write notes about their colors and tactile qualities, and often the aromas and flavors. Thus it is possible, by reading his often minutely detailed journal entries about plants, to appreciate the full scope and intensity of his concentration, the breadth of his awareness, and depth of his curiosity.
Meriwether Lewis made every step of the journey with all of his senses working all of the time. So, of course, did his co-captain and their men, so far as we can tell. The lessons of the Lewis and Clark Expedition are less about adventure, conquest, or commerce, than about concentration and awareness. These are particularly important values to cultivate in this age when most of us are artificially over-stimulated during almost every moment of our waking hours.
1. That study, still a major milestone in the literature, is Paul Russell Cutright's Lewis and Clark, Pioneering Naturalists (Lincoln: University of Nebraska Press, 1969).