Date of this Version
The area in which True Prairie has been most intensively studied lies wholly within the central Missouri Valley. True Prairie is the characteristic vegetation of the western third of Iowa, the eastern third of Nebraska, and adjacent areas in Kansas, Missouri, South Dakota, and Minnesota. The chief communities (consociations) or types have been ascertained and fully described (13). TheAndropogon scoparius type (names of grasses from HITCHCOCK ) was the most extensive of those of uplands and probably exceeded in area all the other grassland types combined. The Sporobolus heterolepis community was of small extent. Stipa spartea was dominant in the remaining upland type, which was somewhat more extensive than the Sporobolus type. The Andropogon gerardi community occupied moist lower slopes and well-aerated lowlands. Elsewhere it was sometimes abundant over limited areas of well-watered, nearly level uplands. The Spartina pectinate community occupied extensive areas of wet, poorly aerated soils such as occur on flood plains. The remaining lowland type, Panicum virgatum-Elymus canadensis, of much less extent, occurred on soils intermediate in water content and aeration between the two preceding types. Since plant communities of flood plains, such as most of those in northwestern Missouri, have recently been fully described (9), they are not included in this study.