[R] axis names in triangle.plot

[Thomas Hoffmann]

Hi folks,

I am using a data.frame with sediment grain sizes:

 > grain
     sand  silt  clay
OAT 10.03 56.77 18.25
OAT 10.40 57.40 17.94
WG1 50.03 20.68 12.57
WG1 43.20 25.69 13.41
WG1 33.89 31.10 14.48
WG2  2.84 62.81 20.79
WG2  2.79 60.46 19.16
WG2 16.27 33.04  6.48
WG2  1.39 57.90  9.13
WG3  4.54 52.91 17.20
WG3  5.20 50.55 15.65
WG3  7.71 49.13 10.80
WG3  4.43 50.03 11.83
WG3  1.72 57.53 14.20
WG3  1.51 58.99 13.96

I would like to do a trinagle.plot with labeled axis-names "sand" "silt" 
and "clay". However using the command:

tringle.plot(grain)

from ade4-apckage) does not plot the axis names and there is no paramter 
to set the labels like "xlab" in the plot command. Does anybody has a 
good advice?

Thanks in advance
Thomas