The Development of the Rye Spike until Emergence

In 1938, Gregory and Purvis proposed a scale of units to evaluate the stage of development in rye plants. This scale, based upon morphological features of the growing point, has now been refined for that part concerning the generative development of the growing point until emergence. After a survey of the spike morphology, a scale of 15 stages, each of about equal duration, is described and its use discussed.