A tepal (PO:0009033) that is part of a collective tepal structure (PO:0025021), along with a fused collective tepal structure (PO:0025138), but is separate from (PATO:0001505) the other tepals. [source: PATO:0001505, POC:curators, POC:Laurel_Cooper]
Comment
A free tepal (PO:0025136) only occurs in a perianth (PO:0009058) that contains a fused collective tepal structure (PO:0025138). If you are describing a tepal (PO:0025137) that is part of a perianth (PO:0009058) where none of the tepals (PO:0009033) are fused, you should use tepal.