Linked from
The 14 pages that link to Perianth, each with the reason it gives.
MagnoliidsRelated: Many magnoliid flowers have numerous, sometimes spiral-arranged perianth parts.
UlmaceaeRelated: Elm flowers have a simple perianth rather than showy petals.
CyperaceaeRelated: Many sedges have reduced or absent perianth parts, unlike showier flowers.
Inferior ovaryRelated: Its attachment above the ovary is a visible feature of epigynous flowers.
Narcissus poeticusRelated: The white perianth segments surround the flower’s corona.