R to use stringr::str_extract g

I have a string in a vector like:

l <- c("0_Mango_10a"  "0_Orange_10b"  "0_Apple_11)

I need to extract Mango_10a, Orange_10b and Apple_11

My current code is :

stringr::str_extract(l, "(?<=_)(:alnum:)+")

And i get Mango, Orange and Apple.

Could any one help me getting the desired results.

Thanks in advance!