Seed Germination of Invasive Phytolacca americana and Potentially Invasive P. acinosa

Phytolacca americana and P. acinosa are alien plant species in Europe. The former is considered invasive and more widespread. In order to develop effective and safe eradication and plant disposal methods, the present research focused on the seed germination of the two species. Fruits of different ripeness of both species were collected (fresh and dry seeds within and without pericarp), after which both the germination and maturation were tested. We also tested the continued maturing of fruits on cut plants and observed the development of fruits on whole plants with a cut taproot (in addition to when only the upper part of the stem with fruit racemes was cut off). In general, the seeds germinated from all stages of fruit ripeness, although the germination of dry seeds was better compared to fresh seeds. P. americana’s seeds germinated better and the fruit ripening on cut plants was also more successful compared to P. acinosa. These results could partly explain the invasive success of P. americana. According to our results, removing all fruiting plants from the eradication site is crucial regardless of the fruit development stage.