R code used to produce the graph shown below.

oldpar <- par() 
plot(hierclust,main="", cex=mycex) 
plot(hierclust.single, main="", cex=mycex) 
cutree(hierclust, k=2)         # Cut tree to get 2 groups 
cutree(hierclust.single, h=5)  # Cut at height 5 
par(oldpar)