RESEARCHES ON THE FORMATIVE COURSES OF THE SPIKE COLLAR OF WHEAT IN SYSTEMATIC EVOLUTION AND INDIVIDUAL DEVELOPMENT

1. The spike collars fall roughly into three categories:Ushape, O-shape, V-shape.2. The spike collar represents the vestige of an abortive terminal leaf sheath in systematic evolution, And a mark of the primordium of a leaf under the first lateral spikelet in individual development. Under given conditions, the spike colhr can be returned to leaf, the internodes of rachis can be turned into internodes of stem, the lateral spikelet can be transformed into a bud, a branch spike or a branch inflorescense.3. There is a U-shape spikelet colhr under the rest each lateral spikelet, it represents the vestige of an abortive bracteal leaf sheath in systematic evolution, and a mark of the primordium of a leaf in individual development. Under given conditions, the spikelet collar can be returned to braeteal leaf.4. When the lateral spikelets occur atavistic variation, the spike collar and the spikelet collar progressively return to leaf sheath, leaf blade, ligule and auricles.5.The lateral spikelet are all metamorphosed buds, the internodes of rachis are all metamorphosed internodes of stem. So the place where the inflorescence and stem meet of wheat remote Ancestor has nota clear boundary line.