Morphological dispersal structures in relation to growth habit in the Compositae

The relationship between gross morphological dispersal structures, growth habit, and weediness is reported for a worldwide sample of 5893 Compositae species from 18 regional floras. A significantly smaller percentage of annual species than perennial species has dispersal structures. Among species with dispersal structures, plumed types are more frequent in perennials while adhesive types are more frequent in annuals. Differences in the occurrence and nature of dispersal structures between perennial herbs, shrubs and trees were minor. Weeds are less likely to have well developed morphological dispersal structures than non-weeds. The data support the idea that dispersal in space may be more important for perennial or non-weedy plants than for annual and weedy plants.