Alternanthera | |
---|---|
Alternanthera caracasana (khakiweed) | |
Alternanthera bettzickiana (calicoplant) | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Caryophyllales |
Family: | Amaranthaceae |
Subfamily: | Gomphrenoideae |
Genus: | Alternanthera Forssk. (1775) |
Species | |
80-200, see text | |
Synonyms [1] | |
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Alternanthera is a genus of flowering plants in the family Amaranthaceae. It is a widespread genus with most species occurring in the tropical Americas, [2] [3] and others in Asia, Africa, and Australia. [3] Plants of the genus may be known generally as joyweeds, or Joseph's coat. [4] Several species are notorious noxious weeds. [5]
These are annual or perennial herbs or subshrubs. While some of the better-known species are aquatic plants, most are terrestrial. [5] They take many forms, from prostrate to erect to floating. The leaves are oppositely arranged. The inflorescence is a spike or a rounded head occurring in the leaf axils or the ends of branches. The flowers have 5 tepals. There are 3 to 5 stamens which are fused into a rim at the bases, and 5 pseudostaminodes, appendages between the stamens that are not true staminodes. The fruit is a utricle containing one seed. [3]
The genus Alternanthera contains both terrestrial and aquatic species. The photosynthetic pathway varies in this genus: Some species undergo C3 carbon fixation, one clade of 17 species has acquired the C4 pathway, and yet other species have an intermediate C3-C4 pathway. [6] [2] [7]
It is not yet clear how many species belong in the genus. Estimates range between 80 and 200. [2] [3] [5] [4] [8] Plants of the World Online accepts 106 species. [1]
As of April 2024, Plants of the World Online accepts the following species: [1]
Many species have been reported as noxious weeds, including A. angustifolia, A. caracasana, A. denticulata, A. nana, A. nodiflora, A. paronychioides, A. philoxeroides, A. sessilis, A. tenella, and A. triandra. [5] The most important species is alligator weed (A. philoxeroides), a South American aquatic plant that has spread to other continents. [5] It is a weed of many kinds of agricultural crops, it is an invasive species that degrades native habitat, and its dense mats of vegetation clog waterways, slowing shipping and increasing flooding. [5] Alternanthera plants are known to produce allelopathic compounds that injure other plants, including crops. [5]
Biological pest control agents now in use to reduce alligator weed infestations include the alligator weed flea beetle (Agasicles hygrophila), the alligator weed thrips (Amynothrips andersoni), and the alligator weed stem borer (Arcola malloi). [5]
A. philoxeroides and A. sessilis are eaten as vegetables in parts of Asia. [5]
Some Alternanthera are used as ornamental plants. [5]
Alternanthera philoxeroides, commonly referred to as alligator weed, is a native species to the temperate regions of South America, which includes Argentina, Brazil, Paraguay and Uruguay. Argentina alone hosts around 27 species that fall within the range of the genus Alternanthera. Its geographic range once covered only the Parana River region of South America, but it has since expanded, having been introduced to over 30 countries, such as the United States, Japan, China, Australia, New Zealand and many more. This invasive species is believed to have been accidentally introduced to these non-native regions through sediments trapped by, or attached to, tanks and cargo of ships travelling from South America to these various areas.
The Gomphrenoideae are a subfamily of the Amaranthaceae.
The Amaranthoideae are a subfamily of the Amaranthaceae. The stamens have anthers with two lobes (locules) and four pollen sacs. The main distribution of the subfamily is in tropical America, in tropical and southern Africa, and in Australia.
Gomphrena is a genus of plants in the family Amaranthaceae. They are known as the globe amaranths.
Iresine is a genus of flowering plants in the family Amaranthaceae. It contains 20 to 25 species, all of which are native to the American tropics. The generic name is derived from the Greek word εριος (erios), meaning "wooly", referring to the trichome-covered flowers. Bloodleaf is a common name for those species that have colored foliage, and these are often cultivated as ornamental plants. Some species are additives to versions of the hallucinogenic drink ayahuasca.
Cleome is a genus of flowering plants in the family Cleomaceae, commonly known as spider flowers, spider plants, spider weeds, or bee plants. Previously, it had been placed in the family Capparaceae, until DNA studies found the Cleomaceae genera to be more closely related to the Brassicaceae than the Capparaceae. Cleome and clammyweed can sometimes be confused.
Pfaffia is a genus of plants in the family Amaranthaceae.
Aerva is a genus of plants in the family Amaranthaceae. Its species are native to the palaeotropics, throughout continental Africa, Madagascar and smaller islands, through parts of the Middle East, India, and southeast Asia. Aerva javanica is an alien in northern Australia.
Sarcomphalus is a genus of plants in the family Rhamnaceae.
Agasicles hygrophila is a species of leaf beetle known by the common name alligator weed flea beetle. It has been used successfully as an agent of biological pest control against the noxious aquatic plant known as alligator weed.
Guilleminea is a small genus of plants in the family Amaranthaceae. They are sometimes known as matweeds. These are prostrate, mat-forming perennial herbs growing from taproots. The genus includes seven species native to the Americas, ranging from Arkansas, Colorado, and California to northern Argentina. The best known species is perhaps Guilleminea densa, the small matweed, which has been introduced to parts of Africa, Australia, and the eastern United States where it is a weed.
Duguetia is a genus of trees and shrubs in the plant family Annonaceae with approximately 90 species in central and South America, and four species in west Africa.
Daphnopsis is a plant genus in the family Thymelaeaceae. It includes 72 species native to the Neotropics. They are shrubs and small trees with tubular or bell-shaped flowers. Individuals are dioecious, with male and female flowers produced on separate trees.
Alternanthera brasiliana, also known as large purple alternanthera, metal weed, bloodleaf, parrot leaf, ruby leaf, Brazilian joyweed, purple alternanthera, purple joyweed, is a flowering plant of the amaranth family that is native to the forests of South America and as well as Central America, ranging from northeastern Mexico to northeastern Argentina. It is grown as an ornamental plant.
Morisonia is a genus of flowering plants in the family Capparaceae, found across the Americas from the United States to Argentina. They are typically shrubs or small trees. The genus was recently enlarged with New World Capparis species due to existing taxonomic instability.
Pedersenia is a genus of flowering plants belonging to the family Amaranthaceae.