Family Description:
These are all very finely branched red seaweeds. Plants are often uniseriate (monosiphonous) filaments, which are corticated by small cells or rhizoids in some species. These filaments are the main axis of the plant. Branching is opposite, alternate, or verticillate (with branches arranged in whorls around the axis). Many branches have determinate growth, and are usually called branchlets, but a few continue to grow to produce new axes like the one bearing them (these continue to be called branches). Tetrasporangia are cruciately or tetrahedrally divided. In some cases, bisporangia (sporangia containing two spores) or polysporangia (sporangia containing many spores) are borne in place of tetrasporangia. Cystocarps are naked or at most surrounded by involucral filaments. Most plants in this family are quite small and require a microscope or very good hand lens to see these diagnostic features.

Species description:
Closely related to Sea Fern is Red Wing. In Ptilota, all branches produce reproductive structures (compare with Sea Fern above). Red Wing is distinguished by having the smaller branch of each pair of ultimate branchlets itself either toothed or branched pinnately. The entire organism is finely branched. Specimens can be small (only about 2.5 cm or 1 in high), but larger specimens occur (up to at least 35 cm or 9 in). Plants are often a very dark red, almost black, especially if they occur in shaded crevices or on north-facing rocks.

This species is a denizen of the low intertidal "red zone," which occurs on moderately protected coasts where kelps are infrequent or lacking at this tidal elevation.

Red Wing and Sea Fern are rich in fat-soluble substances chemically related to mammalian hormones. The role that these substances play in algae is unknown, but the substances are known to be beneficial to humans.

Source:  North Pacific Seaweeds

Synonyms and Alternate Names:
Plumaria filicina
Plumaria tenuis
Ptilota tenuis