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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Amaranthus brownii | 1/2 | https://en.wikipedia.org/wiki/Amaranthus_brownii | reference | science, encyclopedia | 2026-05-05T13:24:46.468203+00:00 | kb-cron |
Amaranthus brownii was an annual herb in the family Amaranthaceae. The plant was found only on the small island of Nīhoa in the Northwestern Hawaiian Islands, growing on rocky outcrops at altitudes of 120–215 m (394–705 ft). It was one of nine species of Amaranthus in the Hawaiian Islands, as well as the only endemic Hawaiian species of the genus. It is now considered extinct. A. brownii was first discovered during the Tanager Expedition in 1923 by botanist Edward Leonard Caum. It differed from other Hawaiian species of Amaranthus with its spineless leaf axils, linear leaves, and indehiscent fruits. It was one of 26 vascular plants on Nīhoa, 17 of which are indigenous, six alien, and three endemic only to Nīhoa; these latter three included A. brownii, the Nīhoa fan palm or loulu, and the Nīhoa carnation. A. brownii was considered the rarest plant on Nīhoa and was not directly observed on the island after 1983. Past expeditions collected plant samples and seeds, but no specimens managed to survive ex situ conservation efforts outside of its native habitat. Consequently, there are no known plants or seeds from A. brownii in any botanical garden. Conservation and recovery plans for A. brownii were proposed by the United States Fish and Wildlife Service (FWS), which administers the island of Nīhoa 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 Nīhoa as a critical habitat for the plant and it was classified as critically endangered on the IUCN Red List. Following a lack of sightings for over 35 years despite intensive surveys, the species was classified as extinct on the IUCN Red List in 2018.
== Taxonomy == The species was first collected during a ten-day visit to the island of Nīhoa by the Tanager Expedition. Botanist Edward Leonard Caum collected the first specimen on June 17, 1923, and a second was collected by cartographer Charles S. Judd[b] on June 20, 1923. Forest B. H. Brown, botanist of the Bayard Dominick Expedition to the Marquesas Islands (1921–1922), helped provide descriptions and comments for some of the species described by Erling Christophersen 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 Nīhoa. The FWS does not recognize a common name.
== Description == Amaranthus brownii was the only endemic species of Hawaiian Amaranthus in the Hawaiian Islands.[a] It was an herbaceous annual plant that grows to a height of 30–90 cm (0.98–2.95 ft) and had narrow, linear leaves, small green flowers, and fruit that held a single, dark red seed. A. brownii was monoecious; that is, the male and female flowers were found together on the same plant. It differed 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 were ovoid and between 0.8–1 mm long and 0.6–0.8 mm wide. The plant is thought to have been anemophilous (pollinated by wind).
== Distribution and habitat ==
Amaranthus brownii had a very limited range; it was found only on the 0.65 km2 (0.25 sq mi) island of Nīhoa, located 275 km (171 mi) northwest of Kauai. It is thought that this endemic plant had probably always been rare and restricted to Nīhoa. Its former habitat is managed by the United States Fish and Wildlife Service and protected as part of the Hawaiian Islands National Wildlife Refuge in the Papahānaumokuākea Marine National Monument. A. brownii was one of three endemic and endangered species only found on Nīhoa, along with the Nīhoa fan palm (Pritchardia remota) and the Nīhoa carnation (Schiedea verticillata). At least nine other native plant species can be found in its habitat, including Hawaiian goosefoot (Chenopodium oahuense), lovegrass (Eragrostis variablis), koali ʻawa (Ipomoea indica), goat's foot (Ipomoea pes-caprae subsp. brasiliensis), Panicum torridum, naupaka (Scaevola sericea), Sicyos pachycarpus, ʻilima (Sida fallax), and Nelson's horsenettle (Solanum nelsonii).