''Ahnfeltia plicata'', the landlady's wig, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

red alga Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Ahnfeltiaceae. It grows in northern parts of the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

Description

The landlady's wig forms tufted

perennial plant A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

s with wiry fronds, branching from a discoid holdfast. The cylindrical fronds branch and are

terete Terete is a term in botany used to describe a cross section that is circular, or like a distorted circle, with a single surface wrapping around it.Lichen Vocabulary, Lichens of North America Information, Sylvia and Stephen Sharnoff/ref> This is us ...

, they branch irregularly in a

dichotomous A dichotomy is a partition of a whole (or a set) into two parts (subsets). In other words, this couple of parts must be * jointly exhaustive: everything must belong to one part or the other, and * mutually exclusive: nothing can belong simultan ...

manner. Each plant is about tall and wide. The holdfast is up to wide and composed of a thin layer encrusting the rock substrate. The frond's reddish-black colour results from the red pigments

phycoerythrin Phycoerythrin (PE) is a red protein-pigment complex from the light-harvesting phycobiliprotein family, present in cyanobacteria, red algae and cryptophytes, accessory to the main chlorophyll pigments responsible for photosynthesis.The red pigmen ...

and

phycocyanin Phycocyanin is a pigment-protein complex from the light-harvesting phycobiliprotein family, along with allophycocyanin and phycoerythrin. It is an accessory pigment to chlorophyll. All phycobiliproteins are water-soluble, so they cannot exist wi ...

. Their colour is so intense that it masks the presence of other pigments, chlorophyll ''a'' and beta-Carotene. Some unique

xanthophyll Xanthophylls (originally phylloxanthins) are yellow pigments that occur widely in nature and form one of two major divisions of the carotenoid group; the other division is formed by the carotenes. The name is from Greek (, "yellow") and (, "l ...

s are also present in this seaweed. The landlady's wig could be confused with ''

Cordylecladia erecta ''Cordylecladia erecta'' is a species of red algae in the family Rhodymeniaceae. It is found in the north east Atlantic Ocean and the Mediterranean Sea and is the type species of the genus. Description ''Cordylecladia erecta'' grows in small tu ...

'' but that species is less common and is thicker with more rigid, regularly branched fronds.

Distribution and habitat

The landlady's wig is found on either side of the north Atlantic Ocean from the middle shore down to depths of about . It grows on hard surfaces and is common on rock covered with sand and also occurs in rock pools. It is sometimes torn from the rock in storms, resulting in floating mats of weed. The base of the fronds continue to grow even when they are detached from their holdfasts.

Biology

The landlady's wig is a slow-growing species that may survive for five to ten years. It has different forms at different stages of its life cycle. On male plants there are spermatangial sori that form swellings on the middle parts of the frond. On female plants there are gametangial sori which are up to long. After fertilization of the

carpogonium The carpogonium (plural ''carpogonia'') is the female organ in the Red Algae (Rhodophyta) which have a highly specialized type of reproduction. It contains the reproductive nucleus. It may contain a number of cells usually without chloroplasts. It s ...

carpospore A carpospore is a diploid spore produced by red algae. After fertilization, the alga's carpogonium subdivides into carpospores, and generally the largest type of spore (larger than bispores, which are larger again than tetraspores Tetraspores are ...

s are formed on the female frond. These produce a second

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

generation, giving rise to a

tetrasporophyte The tetrasporaphyte is a phase in the life history of algae which bear tetrasporangia. This phase is usually morphologically similar to the gametophyte A gametophyte () is one of the two alternation of generations, alternating multicellular orga ...

form that often encrusts pebbles. This produces

tetraspore Tetraspores are red algae spores produced by the tetrasporophytic (diploid) phase in the life history of algae in the Rhodophyta as a result of meiosis.Jones, W.E. Revised and reprinted 1964. A Key to the genera of the British seaweeds.''Field Stu ...

s which develop into new gametophyte plants. The encrusting tetrasporophyte form is known as ''Porphyrodiscus simulans''.

Uses

The landlady's wig is an

edible seaweed Edible seaweed, or sea vegetables, are seaweeds that can be eaten and used for culinary purposes. They typically contain high amounts of fiber. They may belong to one of several groups of multicellular algae: the red algae, green algae, and ...

and was used in the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...

for the production of

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori (''Gracilaria'') and "tengusa" (''Gelidiaceae''). As found in nature, agar is ...

. It can also be eaten raw or cooked and is said to have a crunchy texture and pleasant taste.

References

{{Taxonbar, from=Q4696265 Florideophyceae Species described in 1836