Development of the vascular system of the gynoecium of Anthoxanthum was described. The procambium supplying the gynoecium originally developed isolated from any other procambia of the fertile floret. In stage I, a meristematic core extended from the base of the ovary up to the placenta, but below this core the ground tissue of the rachilla between the sieve-element plexus and the base of the ovary was parenchyma. The meristematic core was continuous with a branch to the anterior wall of the ovary. Longitudinal divisions in continuity with this branch extended it upward as a procambial anterior bundle. A series of longitudinal divisions at the right and left flanks of the rachilla, in continuity with the meristematic core, basipetally extended two flanking rachilla bundles from this core to the sieve-element plexus. Procambia for the two posterolateral bundles also arose in isolation near the insertions of the two styles and differentiated bidirectionally: acropetally into the styles and basipetally into the ovary wall toward the meristematic core. Procambium for the placental bundle developed directly from the meristematic core. Sieve elements for the anterior bundle were initiated in isolation at the base of the ovary in a site homologous to the lowest level of the meristematic core in stage I. From this site the sieve elements differentiated acropetally into the anterior bundle. Whether the isolated site of sieve-element initiation for the anterior bundle was also the site of initiation for the flanking rachilla and posterolateral bundles or whether sieve elements for these bundles arose from an additional isolated site or sites is unknown. Sieve elements of the placental bundle were initiated near their bifurcation from the posterolateral bundles and developed acropetally. The anomalous tracheary elements in the flanking rachilla and placental bundles differentiated last.
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Robinson‐Beers et al. (1987) studied this question.