Regular and customized arrows added to a plot

Regular and customized arrows added to a plot
Adding grid lines to R graphics
Drawing with polygon shapes
Drawing a polygon based on a shape file
A normal curve drawing with additional placed elements
Transparency problems in using images in an R graphic
Incorporating drawings with appropriate transparency
A default histogram and a histogram with set breaks
A default histogram from a factor and a boxplot
A simple bivariate scatterplot with a regression line
A basic pairs plot of the R trees data
A boxplot of CO2 output for Kyoto signatory and non-signatory states with jittered points