I cannot find any references in the scientific literature that report what the most common plant is. Does anyone have any sources? Does anyone know which plant is responsible for the most photosynthesis overall?
Hello. I canot list any species, but I suppose that the most widespread are some representatives of Poaceae - they exist in various ecosystems on different continents and differentiated climate zones.
The question is not focused. Most common plant in which area? You should define the area/geographical area as you know the earth is blessed to have varying ecosystem and no system is unique like other. In this situation, how do you expect the species remain common.
Thank you to everyone for the helpful comments. I would be interested to know if anyone has ideas about how to confirm these suggestions (although I am not in the correct field to investigate this question). In a related question, I also wonder if the total land plant mass of Earth could be calculated, perhaps from satellite images?
As far as I know, if you are looking for the presence/ausence of a earth-plant in the Holartic territory, you should think about Pinus sylvestris, Juniperus communis and Populus tremula. They are the most widespread plants I know.