Margaret, I must apologize in regard to asking if the maidenhair fern could change its black stems in my soil. I should have investigated more carefully. What happened: The maidenhair ferns were completely conquered and overrun by a common fern that loves my garden, and does not have black stems. The blackstemmed fern I bought had fronds rather blunt on the ends, rather than sharply pointed; it has disappeared, conquered by the common one which chose to move to the exact spot where I’d put the maidenhair.
And I’m embarrassed because my friend Judy who knows EVERYthing reads this! Stems not black, but face is red.