Hibiscus: Earth Calling Hibiscus Experts, 1 by Snug_As_Bug_Rug

Snug_As_Bug_Rug wrote:
Rec'd this Hibiscus in the mail today (12/8) and couldn't understand exactly what was lurking on the undersides of the bottom leaves. Does anyone know? Where the leaf meets the stem is black--it's not dirt as I tried rubbing it and it doesn't come off. --perhaps mold? Since the search function is disabled, I couldn't research before applying this inquiry, but any input would be much appreciated.

It did come from what I thought to be a pretty reliable source. Thank You, Snug