Amaranthus brownii
Encyclopedia
Amaranthus brownii is an annual
Annual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...

 herb
Herbaceous plant
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...

 in the Amaranthaceae
Amaranthaceae
The flowering plant family Amaranthaceae, the Amaranth family, contains about 176 genera and 2,400 species.- Description :Most of these species are herbs or subshrubs; very few are trees or climbers. Some species are succulent....

 family. The plant is found only on the small island of Nihoa
Nihoa
Nihoa , also known as Bird Island or Moku Manu, is the largest and tallest of ten islands and atolls in the uninhabited Northwestern Hawaiian Islands . The island is located at the southern end of the NWHI chain, southeast of Necker Island...

 in the Northwestern Hawaiian Islands
Northwestern Hawaiian Islands
The Northwestern Hawaiian Islands or the Leeward Islands are the small islands and atolls in the Hawaiian island chain located northwest of the islands of Kauai and Niihau. They are administered by the U.S. state of Hawaii except Midway Atoll, which has temporary residential facilities and is...

, growing on rocky outcrop
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...

s at altitudes of 120–215 m (393.7–705.4 ft). It is one of nine species of Amaranthus in the Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...

, but the only endemic Hawaiian species of the genus. It was first discovered during the Tanager Expedition
Tanager Expedition
The Tanager Expedition was a series of five biological surveys of the Northwestern Hawaiian Islands conducted in partnership between the Bureau of Biological Survey and the Bishop Museum, with the assistance of the U.S. Navy. Four expeditions occurred from April to August 1923, and a fifth in July...

 in 1923
1923 in science
The year 1923 in science and technology involved some significant events, listed below.-Aeronautics:* Juan de la Cierva invents the autogyro, a rotary-winged aircraft with an unpowered rotor.-Astronomy:...

 by botanist Edward Leonard Caum
Edward Leonard Caum
Edward Leonard Caum was a United States botanist known for his work on plant species in Hawaii.In the 1920s, Caum was working with the Hawaiian Sugar Planters' Association , and with the help of W. W. G. Moir of American Factors, the two helped preserve a collection of Native Hawaii sugarcane...

. A. brownii differs from other Hawaiian species of Amaranthus with its spineless
Thorns, spines, and prickles
In botanical morphology, thorns, spines, and prickles are hard structures with sharp, or at least pointed, ends. In spite of this common feature, they differ in their growth and development on the plant; they are modified versions of different plant organs, stems, stipules, leaf veins, or hairs...

 leaf axils, linear leaves
Leaf shape
In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...

, and indehiscent
Dehiscence (botany)
Dehiscence is the opening, at maturity, in a pre-defined way, of a plant structure, such as a fruit, anther, or sporangium, to release its contents. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent...

 fruits.

It is one of 26 vascular plants
Flora of Nihoa
This is a list of the flora of Nihoa, an island in the Northwestern Hawaiian Islands, part of the City & County of Honolulu in the U.S. state of Hawaii...

 on Nihoa, 17 of which are indigenous, six alien, and three endemic only to Nihoa, including A. brownii, the Nihoa Fan Palm or loulu, and the Nihoa Carnation
Nihoa Carnation
Schiedea verticillata, known as the Nihoa Carnation, is an endangered species of carnation, endemic to the island of Nihoa in the Northwestern Hawaiian Islands, where it was discovered in 1923 by the Tanager Expedition. It has been listed as endangered since 1996.It has stems long, erect or...

. A. brownii is considered the rarest plant on Nihoa and has not been directly observed on the island since 1983. Past expeditions collected plant samples and seeds, but no specimens have managed to survive ex-situ conservation
Ex-situ conservation
Ex-situ conservation means literally, "off-site conservation". It is the process of protecting an endangered species of plant or animal outside of its natural habitat; for example, by removing part of the population from a threatened habitat and placing it in a new location, which may be a wild...

 efforts outside of its native habitat. There are no known plants or seeds from A. brownii in any botanical gardens.

Conservation and recovery plan
Island restoration
The ecological restoration of islands, or island restoration, is the application of the principles of ecological restoration to islands and island groups. Islands, due to their isolation, are home to many of the world's endemic species, as well as important breeding grounds for seabirds and some...

s for A. brownii have been proposed by the United States Fish and Wildlife Service
United States Fish and Wildlife Service
The United States Fish and Wildlife Service is a federal government agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats...

 (FWS) which administers the island of Nihoa as part of the Hawaiian Islands National Wildlife Refuge in the Papahānaumokuākea Marine National Monument. In 1996, the plant was listed by the FWS as an endangered species. In 2003, the FWS designated the island of Nihoa as a critical habitat for the plant and it was classified as critically endangered on the IUCN Red List. The plant is one of 51 endangered or threatened plants in the Hawaiian Islands listed under the Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

.

Taxonomy

The species was first collected during a ten-day visit to the island of Nihoa by the Tanager Expedition
Tanager Expedition
The Tanager Expedition was a series of five biological surveys of the Northwestern Hawaiian Islands conducted in partnership between the Bureau of Biological Survey and the Bishop Museum, with the assistance of the U.S. Navy. Four expeditions occurred from April to August 1923, and a fifth in July...

. Botanist Edward Leonard Caum
Edward Leonard Caum
Edward Leonard Caum was a United States botanist known for his work on plant species in Hawaii.In the 1920s, Caum was working with the Hawaiian Sugar Planters' Association , and with the help of W. W. G. Moir of American Factors, the two helped preserve a collection of Native Hawaii sugarcane...

 collected the first specimen on June 17, 1923, and a second was collected by cartographer Charles S. Judd on June 20, 1923. Forest B. H. Brown
Forest B. H. Brown
Forest Buffen Harkness Brown was an American botanist known for his work on pteridophytes and spermatophytes.- Life and research :...

, botanist of the Bayard Dominick Expedition to the Marquesas Islands
Marquesas Islands
The Marquesas Islands enana and Te Fenua `Enata , both meaning "The Land of Men") are a group of volcanic islands in French Polynesia, an overseas collectivity of France in the southern Pacific Ocean. The Marquesas are located at 9° 00S, 139° 30W...

 (1921–1922), helped provide descriptions and comments for some of the species described by Erling Christophersen
Erling Christophersen
Erling Christophersen was a Norwegian botanist, geographer and diplomat. He participated in and led several notable scientific expeditions in the 20th century, including the fifth Tanager Expedition to Nihoa and Necker Island and the Norwegian Scientific Expedition to Tristan da Cunha .-Early...

 and Caum. They named A. brownii after Brown in 1931 with the publication of their paper "Vascular plants of the Leeward Islands, Hawaii". In the paper they originally described A. brownii as one of 20 vascular plant species on the island of Nihoa. The FWS does not recognize a common name.

Description

A. brownii is the only endemic species of Hawaiian Amaranthus in the Hawaiian Islands. It is an herbaceous annual plant
Annual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...

 that grows to a height of 30–90 cm (0.984251968503937–3 ft) and has narrow, linear leaves, small green flowers, and fruit that holds a single, dark red seed. A. brownii is monoecious; that is, the male and female flowers are found together on the same plant. It differs from other Hawaiian species of Amaranthus with its spineless leaf axils, linear leaves, and indehiscent fruits (fruit which does not open to release seeds when ripe). The fruits are ovoid and between 0.8–1 mm long and 0.6–0.8 mm wide. The plant is thought to be anemophilous (pollinated by wind).

Distribution and habitat

A. brownii has a very limited range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...

; it is found only on the 0.65 km² (0.250966403085148 sq mi) island of Nihoa, located 275 km (171 mi) northwest of Kauai
Kauai
Kauai or Kauai, known as Tauai in the ancient Kaua'i dialect, is geologically the oldest of the main Hawaiian Islands. With an area of , it is the fourth largest of the main islands in the Hawaiian archipelago, and the 21st largest island in the United States. Known also as the "Garden Isle",...

. It is thought that this endemic plant has probably always been rare and restricted to Nihoa. Its habitat is managed by the United States Fish and Wildlife Service
United States Fish and Wildlife Service
The United States Fish and Wildlife Service is a federal government agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats...

 and protected as part of the Hawaiian Islands National Wildlife Refuge in the Papahānaumokuākea Marine National Monument. A. brownii is one of three endemic and endangered species only found on Nihoa, along with the Nihoa Fan Palm (Pritchardia remota
Pritchardia remota
Pritchardia remota is a species of palm endemic on the island of Nihoa, Hawaii, and later transplanted to the island of Laysan. It is a smaller tree than most other species of Pritchardia, typically reaching only tall and with a trunk diameter of . It is the only type of tree on the island and...

) and the Nihoa Carnation (Schiedea verticillata). At least nine other native plant species can be found in its habitat, including Hawaiian Goosefoot (Chenopodium oahuense
Chenopodium
Chenopodium is a genus of about 150 species of perennial or annual herbaceous flowering plants known as the goosefoots, which occur almost anywhere in the world. It is placed in the family Amaranthaceae in the APG II system; older classifications separate it and its relatives as Chenopodiaceae, but...

), Lovegrass (Eragrostis variablis), koali awa (Ipomoea indica
Ipomoea indica
Ipomoea indica is a species of morning glory known by several common names, including Blue morning glory, oceanblue morning glory, koali awa, and blue dawn flower.-Description:...

), Goat's Foot (Ipomoea pes-caprae
Ipomoea pes-caprae
Ipomoea pes-caprae, also known as Beach Morning Glory or Goat's Foot, is a common pantropical creeping vine belonging to the family Convolvulaceae. It grows on the upper parts of beaches and endures salted air. It is one of the most common and most widely distributed salt tolerant plants and...

ssp. brasiliensis), Panicum torridum
Panicum
Panicum is a large genus of about 450 species of grasses native throughout the tropical regions of the world, with a few species extending into the northern temperate zone...

, naupakas (Scaevola sericea
Scaevola
Scaevola is a genus of flowering plants in the Goodenia family, Goodeniaceae. It consists of more than 130 tropical species, with the center of diversity being Australia and Polynesia, including Hawaii....

), Sicyos pachycarpus
Sicyos
Sicyos is a flowering plant genus of the family Cucurbitaceae.Members of the genus are commonly known as burr cucumbers.-Selected species:-Formerly placed here:* Blastania garcini Cogn....

, ilima (Sida fallax
Sida fallax
Sida fallax, known as ilima in Hawaiian, is a species of herbaceous flowering plant in the Hibiscus family, Malvaceae, that occurs on most of the Pacific Islands. The flowers are small, in diameter, have five petals, and are a golden yellow in color. Plants may be erect or prostrate and are found...

), and Nelson's Horsenettle (Solanum nelsonii).

The plant grows during the moist, winter season from December through July in Nihoa's coastal dry shrubland
Hawaiian tropical low shrublands
The Hawaiian tropical low shrublands are a tropical savanna ecoregion in the Hawaiian Islands. These shrublands cover an area of in the leeward lowlands of the main islands and most of the smaller islands, including the Northwestern Hawaiian Islands. The ecoregion includes both grasslands and...

 habitat in shallow soil on rocky outcrop
Outcrop
An outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. -Features:Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of soil and vegetation and cannot be...

s in exposed areas between 120–215 m (393.7–705.4 ft). At the time of its discovery in 1923, botanists first observed the plant growing in great quantity on the ridge
Ridge
A ridge is a geological feature consisting of a chain of mountains or hills that form a continuous elevated crest for some distance. Ridges are usually termed hills or mountains as well, depending on size. There are several main types of ridges:...

s towards Miller Peak and on eastern ridges of the island. Expeditions in the early and mid-1960s failed to identify any specimens, but in 1969, ethnobotanist
Ethnobotany
Ethnobotany is the scientific study of the relationships that exist between people and plants....

 Douglas E. Yen of the Bishop Museum collected specimens near Miller Peak. Derral R. Herbst and Wayne Takeuchi of the FWS collected the last known specimen on July 27, 1980. Carl C. Christensen also visited Nihoa in 1980 to reevaluate endemic species last observed on the Tanager Expedition. Sheila Conant and Mark S. Collins visited Nihoa in 1980 as well; Conant returned twice in 1981, first with Mark J. Rauzon and later with Audrey L. Newman. In 1983, Conant visited the island with Wayne C. Gagné. Conant found A. brownii growing on the island in 1981 and 1983, by which time only two populations of 35 plants were thought to exist: 23 plants were found near Miller Peak and 12 plants in Middle Valley. The two plant populations are separated by a distance of approximately 0.4 km (0.248549094659923 mi).

Prehistoric Polynesian habitation on Nihoa may have initially led to a decrease in the plant population of A. brownii. Major threats to the plant include invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

, fire, and hybridization with other Amaranthus species. Inbreeding is a serious threat, as the small plant population must reproduce within its own circle resulting in genetic defects. A. brownii is also forced to compete with non-native pigweed (Portulaca oleracea), the plant's main alien species threat. In 2002 and 2004, the invasive gray bird grasshopper (Schistocerca nitens
Schistocerca nitens
Schistocerca nitens is a species of grasshopper known by several common names, including vagrant grasshopper and gray bird grasshopper. It is a close relative of the desert locust, which is in the same genus. This grasshopper is native to southern North America including Mexico and the southwestern...

) presented an even larger threat to A. brownii. First recorded on the island in 1977, the increasing population density of gray bird grasshoppers led to massive defoliation on the island, leaving A. brownii at greater risk of predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

. In 2004 alone, an estimated 400,000 gray bird grasshoppers destroyed almost 90% of the vegetation on Nihoa.

Conservation

According to zoologist and conservationist Sheila Conant, A. brownii is important due to its uniqueness in the Northwestern Hawaiian Islands as "the only Hawaiian endemic in this large genus which contains many economically and nutritionally important species." However, in more than a decade of field surveys on Nihoa, no living plants have been identified. Wildlife refuge staff have visited the island during the dry season at least 21 times between 1983 and 1996. The absence of the plant in recent field surveys might be explained by the time of visit. Because winter surveys of Nihoa tend to be difficult and dangerous due to poor landing conditions, surveys have not been conducted during the moist, winter growing season from December through March when the plant is easiest to find. Most of the surveys have been completed during the summer months, when it is easiest to visit Nihoa, but during this time, the stems of A. brownii dry up and cannot be distinguished from other herbaceous plant
Herbaceous plant
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...

s. A seven-day visit to the island in April 2006 still did not find any specimens but botanists are optimistic that the species has survived. Additional winter surveys are required to accurately assess the conservation status of the plant.

Ex-situ conservation
Ex-situ conservation
Ex-situ conservation means literally, "off-site conservation". It is the process of protecting an endangered species of plant or animal outside of its natural habitat; for example, by removing part of the population from a threatened habitat and placing it in a new location, which may be a wild...

 efforts to propagate A. brownii by seed in botanical garden
Botanical garden
A botanical garden The terms botanic and botanical, and garden or gardens are used more-or-less interchangeably, although the word botanic is generally reserved for the earlier, more traditional gardens. is a well-tended area displaying a wide range of plants labelled with their botanical names...

s have been unsuccessful. During the 1981 expedition, A. bronwii seeds were collected by Sheila Conant and presented to the Waimea Arboretum on the Hawaiian island of Oahu
Oahu
Oahu or Oahu , known as "The Gathering Place", is the third largest of the Hawaiian Islands and most populous of the islands in the U.S. state of Hawaii. The state capital Honolulu is located on the southeast coast...

 and the Kew Gardens
Royal Botanic Gardens, Kew
The Royal Botanic Gardens, Kew, usually referred to as Kew Gardens, is 121 hectares of gardens and botanical glasshouses between Richmond and Kew in southwest London, England. "The Royal Botanic Gardens, Kew" and the brand name "Kew" are also used as umbrella terms for the institution that runs...

 in London, England. Although the seeds at the Waimea Arboretum germinated
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

 and grew for a while, no plants survived beyond the stage of seedling
Seedling
thumb|Monocot and dicot seedlingsA seedling is a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle , the hypocotyl , and the cotyledons...

 development. Information about the outcome of the seeds sent to Kew Gardens is unavailable.

A proposal for listing A. brownii under the U.S. Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

 was originally submitted on June 16, 1976, but was withdrawn on December 10, 1979 as out of date and incomplete. It was proposed again on March 24, 1993, and was federally listed as an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 on August 21, 1996. On May 22, 2003, the FWS designated 171 acres (69.2 ha) on the island of Nihoa as a critical habitat for A. brownii, as well as Pritchardia remota, Schiedea verticillata, and two other species also found on Nihoa and other Hawaiian islands, ohai (Sesbania tomentosa
Sesbania tomentosa
Sesbania tomentosa, commonly known as Ōhai, is an endangered species of flowering plant in the pea family, Fabaceae, that is endemic to the main Hawaiian Islands as well as Nihoa and Necker Island. It inhabits low shrublands and, rarely, dry forests, at elevations from sea level to...

) and Mariscus pennatiformis. In the same year, A. brownii was internationally classified as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...

 on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

. As of 2010, A. brownii was one of 51 Hawaiian plant species listed as endangered or threatened under the Endangered Species Act.

Further reading

i at Mānoa|accessdate=2011-05-12}}}}Elele. Newsletter of the Bernice P. Bishop Museum Association|issue=7|publisher=Bernice P. Bishop Museum|pages=3–5}}

External links

  • Amaranthus brownii Christoph. & Caum. Hawaii Biological Survey. Bishop Museum
    Bishop Museum
    The Bishop Museum , is a museum of history and science in the historic Kalihi district of Honolulu on the Hawaiian island of O'ahu...

    . Retrieved May 20, 2011.
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