- 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
Callithamnion Lyngbye 1819
Thalli filamentous, erect, usually short, delicate, tufted, saxicolous or epiphytic. Main axis and major laterals alternately branched; secondary laterals alternate or unilateral, sometimes distichous for short distances. Cells multinucleate. Occasional rhizoids produced by lower cells of branchlets and axis sometimes fusing laterally, sometimes penetrating host if epiphytic. Tetrasporangia tetrahedrally divided, borne singly or in pairs on upper side of branchlets, usually sessile. Spermatangia in flat, colorless tufts, adaxial on laterals. Procarps of 2 fertile pericentral cells serving as supporting cells opposite each other on main branches near apices, 1 of each pair bearing 4-celled carpogonial branch. Each supporting cell after fertilization producing 1 auxiliary cell, this fusing with carpogonium through a connecting cell. Nearly all gonimoblast cells but basal ones forming carposporangia. Gonimoblast globular or irregular, with 2-4 gonimolobes formed from the 2 auxiliary cells; involucre usually lacking.
Callithamnion pikeanum Harv.
Harvey 1853: 230; Smith 1944: 318 (incl. synonymy).
Thalli 10-20(40) cm tall, 1 to several conspicuous axes arising from common holdfasts, frequently intertwined; branches woolly, densely corticated, tannish-red to chocolate brown, dependent on epiphytes and degree of wetness for other colors; penultimate and ultimate branchlets uncorticated, closely alternately branched, overlapping and intertwined with each other, frequently with pointed, spinelike apices; tetrasporangia adaxial on ultimate branchlets, sessile, 70-90 µm diam.; spermatangia unknown; gonimoblasts globular, several gonimolobes occurring together.
Common atop rocks, high intertidal, Alaska to Pt. Dume (Los Angeles Co.), Calif. Type locality: San Francisco, Calif.
The several forms or varieties recognized by Gardner, Kylin, and others are an intergrading series scarcely worthy of mention.
Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.
