How to avoid that xtable flips the x and y axis of a table in the final output?

Question

I work with xtable which turns a table of r into a functionable latex code.

    <<echo=false>>=
attach(warpbreaks)
p2 <- round(tapply(breaks, list(tension), mean), digits=2) %>%
  as.table(.)
@

p2 looks like this:

  L     M     H 
36.39 26.39 21.67 

But the output of the created pdf of this code:

<<echo=false, results=tex>>=
library("xtable")
xtable(p2,
       align = "rr")
@ 

looks (approximately) like this:

      x 
L 36.39 
M 26.39 
H 21.67

Why does it not look like the inital table in r and how can I fix it?