Astroturf of the Ocean
By far the most common of the Astroturf-like green algae found in the intertidal zone of the Monterey-Pacific Grove regions is Cladophora columbiana (Collins) (above, center; flanked by C. scopaeformis and C. graminea). Sparse to thick growths of the little tufts (cm to inches across) are present year-round, mostly attached to rocky substrate. Details specific to the species are less available than the seaweed itself, as an array of difficulties and complications surround the classification of its genus, family, and order, and a conspicuous lack of research has been completed on this quite common local alga. C. columbiana and related species participate in a variety of organism interactions, and play a vital role in intertidal ecosystems. In addition, human society has taken particular interest in the kin of C. columbiana, for purposes both practical and ceremonial.
C. columbiana looks like green stuff on a rock:
Taxonomic classification for C. columbiana and other Cladophora is problematic. The experts have historically disagreed upon which families fall under which orders of algae, when the orders and families in questions relate to Cladophora. Many of the discrepancies at this level have centered around whether or not heterotrichy should be considered a significant evolutionary feature.
Cladophora is characterized by branching green filaments, whether sparse or profuse, in a variety of configurations. The alga can be considered in two parts, a basal, rhizoidal base with short branches forming a sort of mini holdfast to a substrate, and a caudal portion, with erect thalli branching out to form filamentous sheets, dense cushions, or, in certain environments, free-living hollow "balls." The cells making up the simple filamentous branches of the caudal section are multinucleate and contain plenty of pyrenoid-packed chloroplasts.
As well, a certain amount of confusion surrounds the distinction between the various species within the Cladophora genus. The problems in the naming of species have been mainly due to the fact that many Cladophora are simply very hard to tell apart. The morphology of the algae can be altered broadly by environmental conditions, in many cases to the extent that the quantitative factors used to define the different species may be rendered ineffectual by variability among individuals of the same species, depending on the conditions any individual alga may have been subjected to.
Although there is currently no definitive species index, below is the taxonomy of C. columbiana according to Isabella Abbott and George Hollenberg in Marine Algae of California.