Competitiveness of the Exotic Silphium perfoliatum against the Native Urtica dioica: A Field Experiment

Table 2

Parameters surveyed on the central plants in the four years of growth.

Year of growth	Harvest date	Plant height	Projection area	Aboveground biomass	Number of shoots	Number of capitula	Number of fruits
1	18 to 20/9/2019	—	—	x	—	—	—
2	25 to 27/8/2020	x	x	x	x	x	x
3	15 to 16/9/2021	x	x	—	x	x	—
4	22 to 23/8/2022	X	x	—	x	x	—
Investigated species		S. perfoliatum and U. dioica		S. perfoliatum

x = parameter was surveyed in the particular year and — = parameter was not surveyed in the particular year.