- Blue markers: specimen records
- Yellow marker: type locality, if present
- Red markers: endpoints of range from literature
Gigartina Stackhouse 1809
Thalli with peglike or discoid holdfasts; fronds gregarious, relatively elongate, cylindrical or compressed to foliaceous, multiaxial, thickly or sparsely beset with papillate outgrowths, some of these clearly vegetative, others carrying reproductive structures. Medulla of delicate, cobwebby, anastomosing filaments, or with cells of various shapes and sizes. Cortex uniform, relatively thin, the cells small, oval to spherical, in 4-6(15)-celled anticlinal rows. Most species with tetrasporangial thalli similar in size and shape to gametangial thalli; in 2 species (G. agardhii and G. papillata) tetrasporangial plant crustose, not resembling erect thalli. Tetrasporangia developed from innermost cortical cells, cruciately divided, in globose to flattened sori on fertile papillae, or in chains in separate crustose stage. Spermatangia in irregularly shaped, continuous, confluent, superficial patches on papillae, sometimes spreading to flat surface of thallus; in some species entire thallus smooth, mostly without papillae, and lighter in color when spermatangial. Cystocarps making prominent bulges on papillae, in some species changing appearance of sterile thallus completely; firm, dense, internal ring of sterile tissue surrounding carposporangia .
Different species of Gigartina tend to occur in characteristic tidal zones.
Gigartina canaliculata Harv.
Harvey 1841a: 409; 1853: 174; Smith 1944: 278. Gigartina serrata Gardner 1927a: 334; Dawson 1961a: 274.
Thalli annual, from perennial bases, 10-25(44) cm tall; lower portions commonly greenish, upper portions purplish, drying to black; thalli com pressed when young and appressed in flat clumps; mature reproductive thalli erect, the upper portions compressed to terete, growing in extensive clumps with entangled basal portions; lower branches unbranched or little branched, 2-3 mm wide; upper third of erect branches irregularly dichotomously divided, distichous in terminal portions. Medulla filamentous, the filaments irregular; cortex firm, the cells in thick rows; tetrasporangial thalli densely branched upward, bearing short, pointed, papillate, terminal branches, these with sori in slipper-shaped, internal nemathecia lateral to apices; spermatangial thalli also densely branched, the papillae pale, with sori encircling papillae subterminally; cystocarpic thalli with papillae and ultimate branches mostly more widely spaced than in other thalli, the gonimoblasts appearing beadlike to unaided eye, several on each papilla, surrounded by and partly enclosed by sterile branches.
Locally abundant, saxicolous, midtidal to lower intertidal, rarely subtidal, S. Ore. to I. Magdalena, Baja Calif. Type locality: San Francisco, 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.
