A prairie restoration area, or even a butterfly garden, is a perfect laboratory for studying the various ways that plants solve the seed-dispersal problem. Within each group, there is considerable variation, and some plants use more than one. When seed is ripe, it can fall to the ground right where it is. A prairie onion seedhead looks like a big dandelion puffball, with the big black seeds all on the outside of the ball. The seeds are held loosely, and drop off a few at a time as the seedheads blow against each other.
Most grasses do the same, as do brown-eyed susans, coneflowers, and many others.
Birds feed on the seeds, and while they're sitting on the seedhead pulling out seed to eat, they loosen and scatter some. Some plants, like columbine and evening primrose, have cup-shaped capsules full of loose seeds. As the plant blows in the wind, seed spills out a bit at a time, as if it were being shaken from a salt shaker. Plants that usethis strategy often drop their seed over a period of weeks or months through the fall and into winter. When seed drops in winter, it may fall into soft snow, burying it and protecting it from the eyes of birds.