- Blue markers: specimen records
- Yellow marker: type locality, if present
- Red markers: endpoints of range from literature
Gelidium Lamouroux 1813
Thalli cartilaginous, to 30+ cm tall. Axes erect, terete to compressed, variously branched, sometimes strikingly distichous, red to deep purple or black. Plants saxicolous, attached to substratum by branched prostrate axes; proportions of prostrate and erect axes varying; plants sometimes occurring in mats of algal turf with extensive basal parts or in more discrete clumps with 1 or more axes arising from limited basal system. Cortex with several rows of pigmented cells, the smaller toward the outside, mostly 2-12 µm diam., irregularly arranged. Medullary cells in cross section generally rounded, 20-27 µm diam., colorless, compacted or loosely appressed, with or without evident starch granules. Rhizoidal filaments thick-walled, 2-5 µm diam., in medulla and/or cortex, varying in number and position within species and even within single plant. Tetrasporangia in sori at apices of branches, or extending over entire flattened lateral branchlet, or also extending into supporting branch beneath; tetrasporangial branchlets with or without distinct sterile margins; tetrasporangial plants often recognizable by dark, granular appearance of fertile branchlets, this resulting from size and intense pigmentation of spores. Spermatangial sori sometimes apparent as relatively unpigmented areas on apices of branchlets, usually conspicuous by presence of sterile darker margin. Carpogonial filament unicellular, fusing with adjacent cells after fertilization. Mature cystocarps protruding equally on both surfaces of branch, usually with single pore on each surface, rarely with 2 or 3; vegetative growth continuing apically beyond developing cystocarp, making its position more proximal.
The following are known only from the type collections from Calif., and their relationships cannot be ascertained; for the present they must be thought of as doubtful species:Gelidium contortum Loomis (1960), San Francisco; G. umbricolum Dawson & Neushul (1966), Anacapa I.; and G. venturianum Dawson (1958), Ventura Co.
Gelidium coulteri Harv.
Harvey 1853: 117; Smith 1944: 196; Dawson 1953a: 70. Gelidium undulatum Loomis 1960: 4.
Thalli in thick clumps to 10 cm tall, occasionally taller in less exposed sites; erect axes with few major branches but with numerous distichous branchlets, these mostly short and equal in length from base to apex of axis; prostrate axes fewer and less extensive than erect parts; main axes 0.3-1.1 mm broad, 0.2-0.5 mm thick, cylindrical basally, more compressed or flat above; fertile apices often broad and of various irregular shapes.
Abundant intertidally, in dense mats or clumps on rocks, or in tufts on mussel shells, Wash. to Pta. Pequena, Baja Calif. Type locality: Monterey, Calif.
The diagnosis of the "typical" branching pattern for this species is based on selected specimens and is illustrated here. The species varies most in compression of axes, number and length of branches, and size of plants.
Excerpt from Abbott, I. A., & Hollenberg, G. J. (1976). Marine algae of California. Stanford University Press, Stanford, California. xii [xiii] + 827 pp., 701 figs.
