Martian’s daughter is Poppy, and the most supported answer is that her mother is not explicitly named in the available coverage; the show appears to treat Martian and Poppy’s mother as separated or off-screen.

What the show indicates

  • Martian is shown with his daughter Poppy in London.
  • Commentary on the series says Martian and the mother of his daughter are separated.
  • Public recaps and cast guides do not identify a specific mother by name in the material surfaced here.

Why the confusion happens

  • The series also centers on Sami Zahir, Martian’s romantic interest and affair, which can make viewers assume she is Poppy’s mother.
  • But the coverage distinguishes Sami from Poppy’s mother rather than identifying them as the same person.

Plain answer

At this point, the safest answer is: the mother of Martian’s daughter has not been clearly identified in the sourced material, and she does not appear to be Sami Zahir.

TL;DR: Poppy is Martian’s daughter, but her mother is not publicly confirmed in the sources reviewed.