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

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

red alga Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest Phylum, phyla of algae, containing over 7,000 recognized species within over 900 Genus, genera amidst ongoing taxon ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Ahnfeltiaceae. It grows in northern parts of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

Description

The landlady's wig forms tufted

perennial plant In horticulture, the term perennial (''wikt:per-#Prefix, per-'' + ''wikt:-ennial#Suffix, -ennial'', "through the year") is used to differentiate a plant from shorter-lived annual plant, annuals and biennial plant, biennials. It has thus been d ...

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 (geometry), 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 S ...

, they branch irregularly in a

dichotomous A dichotomy () is a partition of a set, 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: nothi ...

manner. Each plant is about tall and wide. The holdfast is up to wide and composed of a thin layer encrusting the rock

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

. 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 Cryptomonad, cryptophytes, accessory to the main chlorophyll pigments responsible for photosynthesis.The ...

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 ...

. 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: (), meaning "yellow", an ...

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

carpospore A carpospore is a diploid spore produced by red algae Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest Phylum, phyla of algae, containing over 7,000 recognized spe ...

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. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

generation, giving rise to a tetrasporophyte form that often encrusts pebbles. This produces tetraspores 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 bro ...

and was used in the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

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" and " tengusa". As found in nature, agar is a mixture of two components, t ...

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

References

{{Taxonbar, from=Q4696265 Florideophyceae Protists described in 1836 Red algae species