Vascular system of male and perfect florets of Phragmites australis (Gramineae-Arundinoideae)

The vascular system in the male and perfect florets of Phragmites of the grass subfamily Arundinoideae was reconstructed from serial cross sections. Components of the vascular system in both florets are nearly alike but for differences related to the presence of the gynoecium. The two collateral traces from the styles merge with the collateral placental bundle to form an amphicribral bundle, the pistil prong, in the ovary below the ovule. The prong descends into the upper plexus, an amphicribral bundle formed by the merging stamen traces in the rachilla. A xylem discontinuity occurs in the placental bundle and in the distal upper plexus. The collateral lodicule traces enter the rachilla and unite with the proximal portion of the upper plexus as the palea traces merge into them. But after contacting the upper plexus, the lodicule traces are again discrete in their continued descent of the rachilla. The two lodicule traces, the three lemma traces, and the three traces from the rachilla extension distal to t...