It would tend to raise it. At first, there would be no change, but as materials from the plant were dissolved, they would increase the density of the water and thus the boiling point.
This increase is miniscule if we're talking about the typical boiling of vegetables. It becomes noticeable when the vegetable is reduced to a puree, however. Boil potatoes, tomatoes, or squash to a thick paste, and the boiling temperature can rise as much as 50C/100F before they burn. Adding sugar or flour would also cause an increase in boiling point.