Achene production, dispersal, seed germination, and seedling establishment of Hieracium aurantiacum in an abandoned field community

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Abstract
Achene dispersal, seed germination, and seedling establishment of Hieracium aurantiacum L. were studied in an 18-year-old abandoned field community. Sexual reproductive output from selected patches declined rapidly after anthesis early in the season. The decrease in the number of achenes produced per head indicated a decline in reproductive output as the season progressed. Most of the achenes collected were deposited within 1 m of the source path. Achenes deposited near the source were larger and had a higher percentage viability than those deposited up to 3 m from the source. Seedling survival was higher within the parent patch compared with that at 5 dm in the adjacent herbaceous vegetation. Germination of the seeds gathered earlier in the season was higher than that of seeds gathered at monthly intervals as the season progressed. Cold treatment enhanced germination of seed produced late in the season but had little effect on seed produced early in the season.