Species accumulation curve: rarefaction

Dear all,

I want to create a species accumulation curve using the method "rarefaction". 
In the helpfile to the function specaccum, it is written: ""rarefaction" finds the mean when accumulating individuals instead of sites." which is exactly what I want. 
However if I use plot(specaccum(x,method="rarefaction")), I will get expected species per sites, with sites on the x-axis instead of individuals .
How can I get a curve drawn with expected species on the y axis and individuals on the x axis?

Cheers Anne