Ulva laetevirens Areschoug = Ulva rigida C. Agardh
Chlorophyta, Order: Ulvales; Family: Ulvaceae. Etymology
The scientific name of the alga, Ulva, is the ancient name originally given to all algae. Since the days of Linnaeus, the name has been dedicated to the algae most dominant in nature. Ulva laetevirens has a harder thallus than other species of Ulva, and hence its name, rigida. The scientific name, laetevirens means ‘greenish’, ‘light green’. Description
The Ulva laetevirens connects to the substrate using a round disk. Usually more than one thallus emanates from the same holdfast. The thallus’ edge has microscopic perforations, some that resemble teeth (several cells each) and some simpler. The cells are scattered and not arranged in rows. The thallus is comparatively thick, and it measures near the holdfast 150 microns in width. Usually 2 Pyrenoids. Size
The thallus varies in size in accordance with environmental conditions. Usually, individuals have thalli ranging between 10-15 cm; however, lengths of 30 cm are not uncommon. The bottom of the thallus measures 117-187 microns in width. Colour
The Ulva laetevirens’ thallus is intense green. Ulva laetevirens -an overview of the central part of the thallus, Cells are usually dispersed and are sometimes arranged. Special features
The characteristics of the Ulva laetevirens include its hard thallus and the proliferation at the edges of the thallus (these can be seen in the field using a magnifying glass).
Habitat The Ulva laetevirens grows in potholes on the abrasion platform and sometimes also in the subtidal zone. Epiphytic individuals have been spotted on snails, Cystoseira bushes or other algae that develop under water. Biology and reproduction
See entry under Ulva. Seasonality and distribution
This species is apparently very common along the coast; Ulva lactuca individuals erroneously described in the region may actually have been Ulva laetevirens. The species is widely distributed and has been spotted in the Mediterranean and along American and South African shores.
In Japan, the Ulva laetevirens is used for human consumption, medicine and cosmetics. As a therapeutic plant, its indications are arthritis and mumps )inflammation of the lymphatic nodes). In cosmetics, it is used to prepare facemasks and to induce skin pore reduction.
Seaweeds of the Eastern Mediterranean Coast
Taxonomy Order: Ulvales; Family: Ulvaceae.
The scientific name of the alga, Ulva, is the ancient name originally given to all algae. Since the days of Linnaeus, the name has been dedicated to the algae most dominant in nature. The Ulva olivascens is coloured green, shading towards olive-green, and hence its scientific name, olivascens.
The Ulva olivascens connects to the substrate through a holdfast from which several flattened thalli emanate. Often, holes can be found in the thallus. A microscopic overview reveals a smooth ‘leaf’ edge. The cells are usually scattered,
and only rarely can small sections of organized cells be seen. Usually a single Pyrenoid.
The size of the thallus varies according to environmental conditions, usually attaining a maximal length of 30 cm; however, lengths of up to 50 cm have been found. The width of the thallus at its bottom is about 110-115 microns.
The green colour of the Ulva olivascens is comparatively light, tending towards olive-green.
To identify the alga accurately, a microscope is required. In
Ulva olivascens P. Dang
Ulva olivascens -an overview of thallus’ middle section, cells usually dispersed.
the field, several flattened thalli can be seen emanating from the same holdfast.
The Ulva olivascens grows in pools on the abrasion platform and sometimes in the subtidal zone. Sightings of the species at depths of up to 50 m. have been reported abroad.
Biology and reproduction
See entry in chapter on Ulva.
Seasonality and distribution
This species is apparently very common, perhaps the most
prevalent in the Eastern Mediterranean. It is widely distributed and is known throughout the Mediterranean
Ulva olivascens -a cross - section of the thallus.
and the North Sea.