package 'corrplot'

I'm using the package 'corrplot' for a figure to be used in an academic
article.
The figure must be black-and-white.
I was able to produce a figure with some shades of grey (less than fifty,
admitedly).
However, the legend is still in red color.
I need the legend be in black color.
How can I get rid of the red color in the legend produced by'corrplot'?

Thank you in advance,
Antonello Preti

Here some code for exemplification.


### call the library

library(corrplot)
library(RColorBrewer)

### toy dataset

data(mtcars)

### assign the dataset to a vector

dat <- mtcars

### corrplot with shades of grey

corrplot.mixed(cor(dat), col = rev(brewer.pal(10, "Greys")))

title("\nCollinearity when r > 0.8")

	[[alternative HTML version deleted]]