Book Description

The components of the vascular systems in the male floret and the female floret of Raddia are described from reconstructed serial, transverse sections. Squat tracheary elements, sieve elements, and intermediary cells comprise the systems. The male floret has six and the female floret three collateral bundles in the rachilla at the floret base that become interconnected into a lower sieve-element plexus with accompanying tracheary elements. Besides contributing to the lower plexus, the rachilla bundles serve as the traces for the lemma and palea. That bundle (bundle 3) which is the trace for the lemma median contributes most of the sieve and tracheary elements to the lower plexus. Supernumerary bundles are associated with bundle 3. Rising in the rachilla from the lower plexus is the upper plexus of sieve and tracheary elements. The circular form of the upper plexus of the male floret is influenced by the two traces from each of the anterior lodicules and by each trace from the three stamens. The trace from the posterior lodicule of the male and female florets does not influence the upper plexus. The bi-arcuate form of the upper plexus of the female floret is influenced by the two, more posterior traces from the anterior lodicules. The three staminodia in the female floret do not influence the upper plexus because they are avascular. At the pistil base is a massive amphicribral bundle, the pistil plexus, that sends down vascular prongs and lobes to merge with the upper and lower plexi. Two posterolateral (stylar) collateral bundles merge with the pistil plexus in a gynobasic manner. A placental bundle ascends from the posterior of the pistil plexus, merges with the chalaza, and exceeds the tip of the ovule before ending in a stylar core. Components of the floret vascular system of Raddia confirm the Olyreae as a tribe of the Bambusoideae that should not be placed in the subfamilies Festucoideae, Oryzoideae, or Panicoideae.