- Blue markers: specimen records
- Yellow marker: type locality, if present
- Red markers: endpoints of range from literature
Illustration from DeCew's Guide to the Seaweeds of British Columbia, Washington, Oregon, and Northern California
Plocamium Lamouroux 1813
Thalli erect, sometimes arising from discoid attachments, most often from stoloniferous, prostrate branches with small attachment disks. Erect branches freely branched, compressed to strongly flattened. Branching sympodial, alternately distichous, pectinate, each pectination with 2-5 branchlets. Branches uniaxial, each cell of axial filaments bearing 2 lateral filaments. Cells cut off from lateral filaments progressively smaller out ward, forming compact cortex. Tetrasporangia in groups in small, usually compound, special branchlets. Spermatangia covering ultimate branchlets; cystocarps without carpostome.
Plocamium violaceum Farl. Farlow 1877: 240; Smith 1944: 264; Dawson 1961a: 221.
Thalli mostly 4-5 cm tall, reddish-violet, usually short and congested, with relatively few long, primary branches arising from mat of stoloniferous branches; main axes 1-1.5 mm diam., branches subcylindrical, with 3-5 orders of pectination; lowermost of each order of branches usually simple, 3-6 mm long, commonly strongly curved toward parent branch; tetrasporangia in compound stichidia; sexual structures as for genus.
Common, mostly on vertical rock faces in areas of heavy surf, midtidal, S. Br. Columbia to Is. San Benito, Mexico. Type locality: Santa Cruz, Calif.
Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.
