I was under my truck last night making sure all the nuts were tight and making sure nothing was leaking and found this. I have never worked on this part and have no clue what it is. You can see int he picture the small round filter should have that 1" hose connected to it, but its not. What part is this? Is is something major and I shouldnt drive my truck until its fixed?

Attached is 4 pictures to view, thanks for any help

 

It's the vent for the evap system, supposed to be open like it is.