Ulva lactuca is commonly called sea lettuce. Its color can range from light yellowish green to darker green, but is most commonly a vivid green underwater. When exposed at low tide or when washed up on a beach, it is typically darker green. Out of the water the seaweed looks like a rather slimy lime-green mass but in the water the alga actually does look very much like young lettuce leaves. Ulva lactuca is vivid green and cellophane thin (only two cell layers thick), and forms light yellowish green to dark green translucent sheets. The soft frond grows as a single, irregular, but somewhat round shaped blade with slightly ruffled edges which are often torn. There can be numerous small holes or perforations scattered throughout. The frond is connected to rocks with a small, almost invisible discoid holdfast, and does not have a stipe. Ulva lactuca may grow to a diameter of 20 to 30 centimeters, although it is freqently much smaller, with larger sheets feeling slightly thicker than smaller specimens.

Ulva lactuca can be found in an array of habitats, but is seen more abundantly in sheltered bays or in protected and semi-protected areas with limited wave action. It is found in tide pools, rock pools, cobble, boulders, and bedrock in mid- to lower levels of the intertidal zone, and also grows in the sublittoral to a depth of over 20 meters. In very sheltered conditions, plants that have become detached from the substrate can continue to grow, forming extensive floating mats or rafts. Ulva lactuca tolerates brackish conditions and can be found on suitable substrata in estuaries. It is present year round, but most abundant in summer and fall.

Ulva lactuca grows well in areas polluted with sewage, as it is a nutrient scavenger, and is also an opportunistic species that can form massive blooms when conditions are right. Certain environmental conditions can lead to the algae spreading over large areas. Non-point source pollution including nutrient runoff from agricultural lands and over-fertilized urban and rural sites are thought to be a contributing factor in sea lettuce blooms. The result is that large quantities of Ulva lactuca are washed up on beaches, where their decay produces methane, hydrogen sulphide, and other gases. As the bloom spreads and begins to die, it can deplete an area (and all of the bottom dwelling plants and animals that live there) of oxygen, and cause massive die-offs of fish and invertebrates.

Link for Seaweed Industry Association

Link for (Pereira, 2010) Handbook Guide

Original publication: Linnaeus, C. (1753). Species plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Vol. 2 pp. [i], 561-1200, [1-30, index], [i, err.]. Holmiae [Stockholm]: Impensis Laurentii Salvii.

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Direct use as food - food, consumed whole (Contains: ash; carbohydrates; fibre; lipids; protein; water.)

Ulva is sometimes eaten as "green laver", but it is considered inferior to purple laver

Health, cosmetics, thalasotherapy, wellness & folk medicine - mineral supplement (Contains: ascorbic acid (vitamin C)

Provide biological, medical and pharmacological activity - treatment of gout

Provide biological, medical and pharmacological activity - inhibitory/suppressive effect

Provide biological, medical and pharmacological activity - treatment of scrofula and podagra

Source of inorganic chemicals and other compounds - source of iodine (Contains: iodine.)

Terrestrial plant and animal production - animal feed (direct)

Terrestrial plant and animal production – fertiliser

Other uses: Ulva lactuca is available in different forms from companies in countries which include the UK, Ireland, France, Germany, Vietnam, China, Canada, and the United States. It is sold both in fresh and dried form, in flakes, powders, and salad mixes. It is a delicate seaweed with a mild flavor. Ulva lactuca is sometimes eaten as "green laver", but it is considered inferior to purple laver. It is used as a seasoning by itself and in blends, and can be found in soups and salads. It is a key ingredient in many cosmetic and personal care items such as soap, lotion, toner, lifting cream, eye cream, lip cream, makeup remover, body polish, bath soaks, anti-aging products, shaving lotion, shampoo, conditioner, and serums. It is also a component in gardening and fertilizer products. Leading cosmetic brands which use Ulva lactuca as an ingredient in anti-aging products cite that it contains a high concentration of amino acids (proline, glycine, lysine) which are the basic components of proteins, and that it has an ability to stimulate the cells in the connective tissues to synthesize collagen. This in turn can improve the skin’s elasticity and reduces lines and wrinkles.

In Portuguese: Alface-do-mar

In Galician: Leituga de mar

In Italian: Lattuga di mare

In French: Laitue de mer

In English: Green laver; sea lettuce

In German: Meerlattich

In Japonese: Aonori

Other names: an glasán, green laver, insalata di mare, laitue de mer, lattuga marina, lechuga de mar, luche verde, Meersalat, sea lettuce, zeesla

Type locality: "in Oceano" [Atlantic Ocean] (Linnaeus 1753: 1163).

Lectotype: LINN 1275.24

Notes: According to Womersley (1984: 141) the type is from the west coast of Sweden. The type is marked "5" and agrees well with Linnaeus's description, and the number five is assigned to Ulva lactuca in Species plantarum (Papenfuss 1960).