- 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
Rhodymenia Greville 1830
Thalli erect or spreading, 2-40 cm tall, usually stipitate from discoid holdfasts, with or without cylindrical stolons; branches firm, bladelike, usually dichotomously or irregularly divided; axial branching sometimes sympodial; medulla of large isodiametric cells grading outwardly to small-celled cortex of 2 or 3 cell layers. Tetrasporangia cruciately divided, scattered over entire blade or branch, or in subterminal or terminal sori, sometimes on small marginal or subterminal bladelets, embedded beneath little-modified cortex or in nemathecia. Spermatangia in small superficial sori; carpogonial branches 3- or 4-celled; base of carposporophyte with small fusion cell; cystocarps prominent, scattered or restricted to branch apices, with thick ostiolate pericarp.
Rhodymenia pacifica Kyl.
Kylin 1931: 21; Dawson 1963a: 461. R. lobulifera Daws. 1941: 137. R. palmettiformis Daws. 1941: 140.
Thalli deep rose, 3-13 cm tall, attached by small, primary discoid holdfasts, these supplemented by spreading, more or less prominent stolons; with 1 to several dichotomo-flabellate blades on compressed stipes 1-3 cm long; blades 2-6 times dichotomous at irregular intervals of 1-2.5 cm; divisions 3-13 mm wide, 140-230 µm thick, often terminally broadened and blunt; medulla of +/- 3 layers of large cells, grading through 3 subcortical layers to small cells of outer cortex; tetrasporangial sori in nemathecia, these borne terminally in somewhat expanded blade apices or on lateral or marginal bladelets; spermatangial sori superficial, discoloring the terminal blades; cystocarps aggregated marginally on terminal divisions.
Frequent to common on rocks, lower intertidal and below, N. Br. Columbia to N. Baja Calif.; in Calif., from Humboldt Co. to San Diego. Type locality: Pacific Grove, Calif.
Extremely variable in height, branching pattern, and shape of divisions, but generally broader in branch width than most other Calif. species (except R. palmata var. mollis).
Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.
