Relative Promptness of Nodule Formation among Vetches, Vetchlings, Winter Peas, Clovers, Melilots, and Medics 1

THE conditions under which root nodules develop most readily on lthe roots of leguminous plants have been less intensively studied than the importance of the subject warrants. The more elaborate of the investigations have been conducted in the laboratory, where ̄ the host legum.es necessarily have been subjected to highly artificial conditions. These and other considerations pointed to the need for supplementary investigations to supply data on the development of root nodules under field conditions, hence a series of field experiments has been conducted for a number of years on the Experiment Station ~arm at Auburn, Ala. 3 This paper is a report on one of a series of field studies to determine to what extent, if at all, winter legumes differ among themselves in their promptness or tardiness in developing root tubercles when planted in the field at usual or typical dates in the fall.