Anatomical diversity of funicles in Leguminosae.

To clarify the diversity in funicular internal structures in Leguminosae, 59 legume species (classified into 46 genera, 20 tribes, and 3 subfamilies) were examined by a paraffin-sectioning method. The vascular bundles of legume funicles were clarified as collateral, amphicribral, or amphivasal. In species in which the funicular vascular bundle was collateral throughout the funicle, the xylem is positioned at the pericarpial side in the basal part of the funicle, and the xylem was always positioned at the micropylar side of the phloem in the apical end of the funicles. Whenever the seed direction (from hilum to the micropyle) faces the stylar side, the funicular vascular bundle appears to twist between the basal and the apical part of the funicle. This twist would involve a rotation of the seeds (ovules) during seed (ovule) development. This also may mean that the direction (from hilum to the micropyle) of legume seeds originally faces the pericarp.