The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral- or ribbon-shaped in different species. Most of the members have one or more storage bodies called pyrenoids located in the chloroplast. Pyrenoids contain protein besides starch. Some green algae may store food in the form of oil droplets. They usually have a cell wall made up of an inner layer of cellulose and outer layer of pectose.
Brown algae are a large group of multicellular algae comprising the class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar regions. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Most brown algae live in marine environments, where they play an important role both as food and as a potential habitat. For instance, Macrocystis, a kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater kelp forests that contain a high level of biodiversity. Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Some members of the class, such as kelps, are used by humans as food.
The Zygnemataceae are a family of filamentous or unicellular, uniseriate (unbranched) green algae. The filaments are septated and reproduction is by conjugation; Spirogyra is commonly used in schools to demonstrate this kind of reproduction. The family is notable for its diversely shaped chloroplasts, such as stellate in Zygnema, helical in Spirogyra, and flat in Mougeotia. The Zygnemataceae are cosmopolitan, but though all generally occur in the same types of habitats, Mougeotia, Spirogyra, and Zygnema are by far the most common; in one study across North America, 95% of the Zygnemataceae collected were in these three genera. Classification and identification is primarily by the morphology of the conjugation, which is somewhat rare to find in natural populations of permanent water bodies; when in the vegetative state, the rarer genera resemble the three most common, and are often mistaken for them and catalogued as such. Conjugation can be induced in low-nitrogen culture. While they occupy many habitats, in North America all are found solely in freshwater or subaerial habitats. Species typically exist as floating mats in stagnant water in ditches and ponds, but some also grow in moving water, attaching themselves to a substrate by rhizoid-like projections of the basal cells of the filament. The mat species rise to the surface in early spring, grow rapidly through the summer, disappearing by late summer. Members of the Zygnemataceae, such as Spirogyra, fall prey to parasites, especially chytrids. Most genera previously assigned to Mesotaeniaceae as well as the Desmidiales actually emerged in the Zygnematacae.
Oedogonium is a genus of filamentous, free-living green algae. It was first discovered in the fresh waters of Poland in 1860 by W. Hilse, and later given its name by German scientist K. E. Hirn.
Dictyotales is a large order in the brown algae containing the single family Dictyotaceae. Members of this order generally prefer warmer waters than other brown algae, and are prevalent in tropical and subtropical waters thanks to their many chemical defenses to ward off grazers. They display an isomorphic haplodiploid life cycle and are characterized by vegetative growth through a single apical cell. One genus in this order, Padina, is the only calcareous member of the brown algae.
Characiochloridaceae is a family of green algae in the order Chlamydomonadales.
Botryococcus is a genus of green algae. The cells form an irregularly shaped aggregate. Thin filaments connect the cells. The cell body is ovoid, 6 to 10 μm long, and 3 to 6 μm wide. Fossils of the genus are known since Precambrian times, and form the single largest biological contributor to crude oil, and are a major component of oil shales.
Asteromonas is a genus of green algae in the family Asteromonadaceae. It has been described from saline, marine, and brackish environments. It is closely related to the genus Dunaliella, another genus common in saline waters.
Atractomorpha is a genus in the Sphaeropleaceae, a family of green algae. The genus name is derived from Greek and means "spindle-shaped" or "arrow-shaped", and refers to the shape of the cells.
Characiochloris is a genus of green algae in the family Characiochloridaceae. Characiochloris is epiphytic on freshwater algae, or found in soil.
Chlamydopodium is a genus of green algae in the family Characiochloridaceae. It has been recorded from soil or attached to algae or zooplankton.
Draparnaldia is a genus of freshwater green algae in the family Chaetophoraceae. Draparnaldia are uniseriate; each filament is composed of a chain of cells arranged in one row. Chloroplasts appear as a band within the center of each cell. The length of the main axis cells are generally the same, regardless of whether or not they bear branches. These side branches are divided extensively into terminal hairs. The entire plant is enveloped in loose, slippery mucilage. Draparnaldia is a cosmopolitan genus with wide distribution and it is usually found in cold aerated waters. They are either attached to sand or grow epiphytically on other aquatic plants. Draparnaldia can be seen growing in clear streams trailing on stones and boulders. Herman S. Forest of The Southern Appalachian Botanical Club has stated that while not common, it is present frequently enough to be recorded in almost all local flora lists of green algae that have been compiled. A multitude of species are present in Lake Baikal, Siberia and have been described by Meyer and Jasnitzky. A species of the genus had been placed and described in the Linnean Herbarium as Conferva mutabilis Roth in 1797. Nowadays Conferva is no longer used and the species is described as Draparnaldia mutabilis (Roth) Bory. Bory is added in honour of the researcher of the same name, based on whose description the genus was separated from similar appearing forms. Bory is accredited with the establishment of the genus.
Podohedriella is a genus of green algae in the family Selenastraceae. It is found in freshwater habitats or on damp wood.
Sorastrum is a genus of green algae in the family Hydrodictyaceae. It is a component of the phytoplankton of freshwater ponds, lakes, and ditches. Sorastrum is common in tropical to temperate regions of the world, but due to its small size it is often overlooked.
Sphaeroplea is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Desmidium is a genus of green algae, specifically of the Desmidiaceae.
Zygnematophyceae is a class of green algae in the paraphylum streptophyte algae, also referred to as Charophyta, consisting of more than 4000 described species. The Zygnematophyceae are the sister clade of the Embryophyta.
Bangia is an extant genus of division Rhodophyta that grows in marine or freshwater habitats. Bangia has small thalli with rapid growth and high reproductive output, and exhibits behavior characteristic of r-selected species. The plants are attached by down-growing rhizoids, usually in dense purple-black to rust-colored clumps. The chloroplasts of Bangia, like others in the division Rhodophyta, contain chlorophyll a and sometimes chlorophyll d, as well as accessory pigments such as phycobilin pigments and xanthophylls. Depending on the relative proportions of these pigments and the light conditions, the overall color of the plant can range from green to red to purple to grey; however, the red pigment, phycoerythrin, is usually dominant.
Klebsormidium is a genus of filamentous charophyte green algae comprising 20 species. The name was proposed in 1972 to resolve confusion in application and status of Hormidium and was given for the German botanist Georg Albrecht Klebs.
Scytothamnus australis is a brown alga species in the genus Scytothamnus found in New Zealand. It is a sulphated polysaccharide and the type species in the genus.
