Erechtites hieracifolia reproduction biology
Erechtites hieracifolia (Asteraceae) is an annual herb originating from temperate North America which is naturalized in central Europe (known to occur in Austria, Czech Republic, Hungary, Romania and Serbia). It is considered an invasive neophyte in Hungary as it is found to be abundant in forest cuttings three or four years after the trees have been harvested. It can reach up to 2 m high and is thought to compete with other species for light, water and nutrients. Studies on the biology of the plant have shown that each individual produces on average 253 inflorescences, each with 130 achenes, meaning that a single plant could produce over 30,000 seeds. Achenes germinate all year long except in September and October. Its seed bank does not persist for a long time, although viability of seeds for longer than eight years has been observed in North America.
Sources
Csiszár Á (2006) Study of the generative reproduction of the fireweed (Erechtites hieracifolia RAF. Ex DC.) In: Neobiota. From Ecology to Conservation. 4th European Conference on Biological Invasions. Vienna (Austria), 2006-09-27/29, BfN-Skripten 184: page 101 (abst.).