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:
The erect axes of Coarse Sea Lace are about 1 mm in diameter and up to 20 cm (8 in) tall. Most specimens are only 10 to 15 cm (4 to 6 in) high, however. They appear olive gray to brownish red or dark red and carry five or six orders of branching mostly in one plane.

The lateral branches are distinctly arched and carry branchlets along only their upper side. These occur mostly in the upper two thirds of the individual, while the lower third is almost naked. A prostrate branch serves as a holdfast. The branches are corticated and, unlike in some closely related species, in Coarse Sea Lace this cortication is not thicker at nodes and thinner between them. The ultimate branchlet tips are shaped like little crab pincers.

Male and female gametophytes are separate individuals. Tetrasporangia occur on the slightly inflated tips of the branchlets and are usually crowded together.

Coarse Sea Lace prefers to grow on rocks that are somewhat to very exposed to surf. It has been found in association with Sea Palm (Postelsia palmaeformis), and sometimes grows on the surfaces of other species of algae.

Source:  North Pacific Seaweeds