EXPLORATION in the Missouri country was commenced in 1835 by Karl Andreas Geyer, a collector who became well known for his botanical explorations in the northwestern section of the United States. His explorations extended over a number of years and ranged from Illinois westward to the Pacific. He traveled especially in the territory included between the Mississippi and the Missouri River as far north as North Dakota.
Karl Andreas Geyer  was born in Dresden, Germany, on November 30, 1809. His father was a market gardener of very moderate circumstances. The boy was naturally bright and studied Latin under the tutelage of a kind-hearted man who helped him with his lessons, which were studied while he was selling hi;? father's produce in the streets of the city. In 1826 he entered the garden at Zabelitz as an apprentice. In 1830 he removed to Dresden and engaged as assistant in the botanic garden there. In this place he had numerous friends, among whom was Dr. H. G. Reichenbach, whose lectures upon botany he attended with great regularity. He seems to have been a very likable and attractive person, drawing the attention of those with whom he came in contact. In February, 1834, he left Dresden for America. Here he collected plants during the summer months and worked at odd jobs in the winter, thus maintaining himself for several years. In one case he entered a newspaper office as compositor, but a few months later he was writing the leading articles for the same paper that he had helped set in type.
Geyer's first great journey in this country was in 1835, when he visited and explored the plains of the Missouri with a single companion. In 1836 and the succeeding years he went with Nicollet surveying the country between the Missouri and the Mississippi River. In 1840 he collected around St. Louis and in Illinois, making very considerable collections during this season. While in St. Louis he became acquainted with Dr. George Engelmann and this friendship seems to have lasted as long as Geyer was in this country. Engelmann seems to liave worked over his collections, as we find him publishing upon them
- Anonymous, Chronik des Garteniwesens, 3: 185-187, 1853.
Reichenbach, H. G., Kew Garden Miscellany, 7: 181-183, 1855.