Germination of the Dimorphic Fruits of Bidens Pilosa L.

Summary Dimorphic fruits of Bidens pilosa were tested separately for differences in germinability and seedling development. The long achenes were found to germinate readily under a wide range of conditions while the short achenes showed fairly exacting germination requirements. Germination of the short achenes was found to be enhanced by red light treatment, scarification, applied hormones, leaching and increased oxygen tensions. Seedlings originating from short achenes showed lower survival rates and initially slower development than those originating from the long achenes. The implications of the morphological differences and differences in germination and development of the two achenes are discussed.