Working with regular expression

Hello again,

I was trying to extract the date element from a character vector using
Regular expression. Below is a sample what I was trying to do:

Text <- c("asdf May 09 2009", "dsaf_01-01-2001")
gsub("[a-zA-Z_]", "", Text)

[1] "  09 2009"  "01-01-2001"


I basically have a long text and the task is to extract the date
element. My above strategy failed because I can not extract the month
for the first element.

Can somebody help me out?

Thanks and regards,