Morrison has joined the show this season as Zoey, a new love interest for Ted (Josh Radnor).
However, she admitted that she doesn't know if her character is the mother mentioned in the sitcom's title.
"It's not even that I can't say, but I just have no idea," she told TV Guide. "It's always so funny because people think we have information that we don't, you know? I have no information and I'm glad I don't know because I'd rather not have to lie about it."
However, Morrison confirmed that Zoey will be a "very important and large" part of Ted's life and suggested that the pair have "fun banter".
She added that she "can't even think about" the fact that Zoey is the mother, saying: "Honestly, I'm just happy to be part of [the show]. I think [executive producers Craig Thomas and Carter Bays] have done such an awesome job of keeping the show amazing and funny. There's no way in the world I could possibly think of something funnier or better. Even if she's not the mother, I think Ted has met his match."
How I Met Your Mother continues on Mondays at 8/7c on CBS.