- Blue markers: specimen records
- Yellow marker: type locality, if present
- Red markers: endpoints of range from literature
Herposiphonia Nägeli 1846
Thalli of indeterminate prostrate branches attached by frequent unicellular rhizoids, these out off as separate cells from distal end of pericentral cells. Primary indeterminate branches bearing determinate and indeterminate branches in more or less regular sequence, mostly with 3 determinate branches between successive indeterminate branches, these alternate on either side of axis. Mature determinate branches distichous or erect and parallel, with or without trichoblasts, mostly with characteristic number of pericentral cells for given species. Cells with numerous small, discoid chloroplasts usually randomly distributed. All branches uncorticated. Tetrasporangia in straight series, 1 per segment in determinate branches, tetrahedral or obliquely cruciate. Spermatangial stichidia cylindrical, on determinate branches, usually several per branch, without sterile apices and without accompanying trichoblasts. Cystocarps ovoid to somewhat urceolate, on determinate branches.
Herposiphonia verticillata (Harv.) Kyl.
Polysiphonia verticillata Harvey 1833a: 165. Herposiphonia verticillata (Harv.) Kylin 1925: 74; Smith 1944: 370.
Thalli primarily prostrate and somewhat matted, with some free branches 1- 2 cm long, dark reddish- brown; 3 alternating determinate branches between successive indeterminate branches, and no bare nodes; determinate branches arising distichously but soon mostly curved and variously directed; indeterminate branches mostly remaining rudimentary; main axes 200- 300 µm diam., with 14- 16 pericentral cells, the segments mostly shorter than diam., determinate branches 1-1.5 mm long, 100-200 µm diam., usually thickest in middle, terminally acute, frequently narrowed at base, the segments shorter than broad, with 10-12 pericentral cells; tetrasporangia +/- 80 µm diam., not distending segments; spermatangial stichidia 200-250 µm long, borne adaxially in groups of 3-8, usually with 1 sterile terminal cell.
Common epiphyte, low intertidal, Duncan Bay, Br. Columbia, and San Francisco, Calif. to Pta. Santa Rosalia, Baja Calif. Type locality: "California," probably Monterey.
Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.
