Is it a zombie? Is it an alien?

No, it's Honesty.

Honesty grows in the garden
with a face as pale as a ghost.
Once it was rosy, a purply pink;
now it's as white as a post.

Tomorrow its face will be silver,
like a fairy-coin it will seem.
It will spend its seeds in the soil below,
and then lie down to dream.

Honesty dies in the winter,
as if truth were a thing of the past.
But in the spring, it will burst afresh:
Honesty's made to last.