library(colorspace)
branchvar <- 1
tree <- function(x, y, branch) {
  lines(x,y,col=hex(RGB(0.1,0.4,0)))
  wadd <- 0.7
  if(branch>0) {
    alpha <- atan2((y[2]-y[1]),(x[2]-x[1]))
    len <- sqrt((y[2]-y[1])^2+(x[2]-x[1])^2)*0.6
    tree(c(x[2],x[2]+abs(rnorm(1,1,branchvar))*len*cos(alpha)),
          c(y[2],y[2]+abs(rnorm(1,1,branchvar))*len*sin(alpha)),
          branch-1)
    tree(c(x[2],x[2]+len*cos(alpha+wadd)),
          c(y[2],y[2]+len*sin(alpha+wadd)),branch-1)
    tree(c(x[2],x[2]+len*cos(alpha-wadd)),
          c(y[2],y[2]+len*sin(alpha-wadd)),branch-1)    
  } else {
    points(x[2],y[2],pch=16,
             col=hex(RGB(rbeta(1,2.6,0.5),rbeta(1,0.5,3),0)))
  }
}

plot.new()
tree(c(0,0.20),c(0,0.20),7)