If you read monographs of hibiscus (Hibiscus sabdariffa), you'll often see a note about how the plant is rich in vitamins and minerals, including iron. In this episode, I share some research I came across recently suggesting that a typical water infusion of the calyces (about 12 g) yields only ~1.25 mg iron and of that roughly 30% is extractable (0.375 mg), leading to the conclusion that hibiscus is not a substantial source of dietary iron.
It's still a lovely herb for so many other reasons, but it's probably for the best if we don't imply that it's a good source of iron!