The early Stages of Development in the Rye Spike

In this paper a description is given of the normal course of development of the rye plant. Symbols are used to indicate the successive stages of development. In agreement with Blaauw and co-workers the indications Stadium I (vegetative phase) and Stadium II (beginning of reproductive phase) are maintained. To distinguish the earlier stages of the reproductive phase, use is made of abbrevations of the botanical name of the organs whose development in a certain stage is characteristic for what one observes. Stadium I: Growing point vegetative; only leaf initials present. Stadium II: Elongation of the growing point; beginning of the reproductive phase. Spike length ± 1 mm. Stadium Spi: Spikelet primordia developing. Stadium Gl: Initiation of the empty glumes on both sides of spikelet primordia. Stadium Pr: First flower primordia become visible. Spike length d: 2 mm. Stadium An: Primordia of anthers become visible. Stadium Ar; Rapid elongation of the awn on the flowering glume of flowers of the first order. Flower primordia of higher order become visible. Spike length ± 5 mm. Stadium Th: Anther primordia of (lowers of the first order are divided into two thecae. Spike length J; 8 mm. For older stages it is recommended to use the classification of Feekes (1941).