size of unit key in star plots

Hi Everyone

I'm struggling with star plots at the moment. I've got R to plot my segment diagrams, but when I ask it to add the unit key, it plots a tiny tiny star as my unit key compared to the other stars.

I realize that this is because of the scaling, but how can I avoid it? At higher values of 'len' my plots lie on top of each other.

Does anyone know how to change the size of (just) the unit key?

This is the code so far:
stars(mydata, scale = FALSE, len = 0.015, draw.segments = TRUE, key.loc = c(5.5, 2.2))