Annals of Botany 116: 149–187, 2015
Since the publication of this paper, it has become apparent that there was an error on line 6 of the Discussion (page 177), where 1 g is wrongly defined in terms of microGals. The statement: 1 g = 9·81 × 10–8 μGals should be 1 g = 9·81 × 108 μGals.
The author would like to apologize for this error.
