How do I edit the dendrogram whilst using heatmap.2 function in r

I am trying to create a heatmap to represent the change of gene expression over a period of time. the code I have used is this:

coul <- colorRampPalette(brewer.pal(8, "Reds"))(25)
heatmap.2(dm, dendogram=c("row"),Colv=NA, xlab="Time points", ylab="Genes of interest", scale="row", col=coul, tracecol = NA) 

As one cant really see the branches of the dendogram that well, I was wondering whether you can somehow stretch it out to become more visible?

I was also wondering how to remove the "colour key and histogram" label. Many thanks!