Orthodox descriptions of the grass family contain the statement "stems usually (or mostly) hollow." This characterization has been generally accepted as applying to all mature grasses other than the genera grouped under the tribes Andropogoneae and Nazieae, which are usually cited as exceptions. My own conception of the stem structure of grasses conformed to this description until early in 1927 when certain grasses, not members of either of the excepted tribes, were found to have solid stems. This discovery led to further investigations, the results of which show that a very high percentage of the mature grasses native to the Jornada plains in southern New Mexico have solid internodes.