Hymenachne amplexicaulis | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Clade: | Commelinids |
Order: | Poales |
Family: | Poaceae |
Subfamily: | Panicoideae |
Genus: | Hymenachne |
Species: | H. amplexicaulis |
Binomial name | |
Hymenachne amplexicaulis (Rudge) Nees | |
Hymenachne amplexicaulis, also known as West Indian marsh grass in the US, Olive hymenachne in Australia, and hereafter referred to as hymenachne, is New World species [1] in the genus Hymenachne . Hymenachne is from the Greek hymen meaning "membrane" and achne meaning "chaff, glume, scale" and amplexicaulis is from Latin, literally "embracing the stem" or "stem-clasping. [2] [3] This freshwater species is native to the tropical and subtropical regions of the West Indies, Northern South America, and Central America. [4]
Hymenachne is a perennial grass that primarily reproduces via stolons. [4] This robust species is commonly found growing 1–2.5m tall. [4] The stems are hairless and float prostrate across the top of the water, then grow upright from these bases to support leaves. [4] The flat, triangular leaves (10–45 cm long, up to 3 cm wide) have a prominent clasping bases, or auricles. [4] The auricles help to distinguish it from other invasive wetland grasses and the native H. acutigluma in Australia. [5] Hymenachne has been shown to increase the stem length between nodes to keep leaves above water during periods of flooding. [6] Its stem is packed with airy tissue called aerenchyma to help the stems float and to aid in flood tolerability. [5]
Hymenachne flowers in the early fall and seeds in late fall. [7] The flower is a panicle [8] that can grow to half a meter. [5] Researchers at the University of Florida have seen multiple panicles per plant originating from branching at a single node. [9] Hymenachne can produce thousands of seeds with up to 98% germination right off the panicle. [10] [11] [12]
Hymenachne prefers constantly inundated soil and is known to survive comfortably in about a meter of water for 20 years. [5] [13] This species was shown to survive poorly in Australia where flooding exceeded 1.2 m. [14] [12] In its native range in Venezuela, and in invaded areas of Florida, hymenachne was documented to survive in >1.2m of water for nearly a year. [15] [16] Hymenachne has also been found in water greater than 4m deep persisting in floating mats, likely dislodged after a storm event. Conversely, hymenachne is not recorded to survive sites that entirely desiccate. [17]
Hymenachne is known to colonize and form dense monocultures in floodplains, roadside ditches, and lake margins in invaded and native areas. [14] [18] [19] [4] It is often found colonizing areas with little shading and competition from other species. [5] Although limited information is available on soil preferences of hymenachne, it has been found in deep, poorly drained muck soils in Florida. [20] It is not found in waters with a significant salt concentration. [21] [5]
There have been three introductions of hymenachne into Australia, one in Florida, and one in Louisiana. [22] [23] [5] Australia now lists hymenachne as one of the top twenty worst weeds. [24] Hymenachne invasions have been shown to decrease species richness, increase invasive fish populations, and overall cause fundamental changes in floral and faunal composition in Australia. [13] Hymenachne was introduced in Australia as forage for cattle, and likely for the same reason in Florida. [5] The species was used in ponded pastures, or artificial ponds created to hold water for use in the dry season. [5] High reproducibility from stem fragments aids in the dispersal and invasion of this species. [10] The first herbarium record of hymenachne in Florida is from 1957. [23] [25] The second specimen is not recorded until 1977. [25] The cause for this gap is unknown; however, today it is recorded in 28 counties across the state. [26] [27]
A swamp is a forested wetland. Swamps are considered to be transition zones because both land and water play a role in creating this environment. Swamps vary in size and are located all around the world. The water of a swamp may be fresh water, brackish water, or seawater. Freshwater swamps form along large rivers or lakes where they are critically dependent upon rainwater and seasonal flooding to maintain natural water level fluctuations. Saltwater swamps are found along tropical and subtropical coastlines. Some swamps have hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodic inundation or soil saturation. The two main types of swamp are "true" or swamp forests and "transitional" or shrub swamps. In the boreal regions of Canada, the word swamp is colloquially used for what is more formally termed a bog, fen, or muskeg. Some of the world's largest swamps are found along major rivers such as the Amazon, the Mississippi, and the Congo.
A savanna or savannah is a mixed woodland-grassland ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses. According to Britannica, there exists four savanna forms; savanna woodland where trees and shrubs form a light canopy, tree savanna with scattered trees and shrubs, shrub savanna with distributed shrubs, and grass savanna where trees and shrubs are mostly nonexistent.
Macroptilium atropurpureum, commonly referred to as purple bush-bean, or siratro is a perennial legume recognized by its climbing, dense, green vines and deep purple flowers. The plant is indigenous to the tropical and subtropical regions of North, Central, and South America, as far north as Texas in the USA and as far south as Peru and Brazil. It has been introduced for use as a food for stock to many tropical regions around the world. It has become an invasive pest plant in a number of areas, including the north-eastern coast of Australia. Rich in protein, M. atropurpureum is commonly used for cattle pastures intercropped with grass, used in hay, or as a ground cover to prevent soil erosion and to improve soil quality.
Scottsdale Reserve is a 1,328-hectare (3,280-acre) nature reserve on the Murrumbidgee River in south-central New South Wales, Australia. It is 79 kilometres (49 mi) south of Canberra, and 4 kilometres (2.5 mi) north of Bredbo. It is owned and managed by Bush Heritage Australia (BHA), which purchased it in 2006. The purchase was supportive of projects aiming to connect existing fragmented remnant habitat such as K2C. Since the 1870s up until 2006, the land was used for agriculture – primarily sheep grazing with some minor cropping. A significant component of the Reserve has been cleared of native vegetation.
Sacciolepis is a genus of plants in the grass family. Cupscale grass is a common name for plants in this genus.
Hymenachne is a genus of widespread wetlands plants that is in the grass family. They are commonly known as marsh grasses. They are distributed in tropical and subtropical regions of Asia, the Americas, and the Pacific Islands. A species from the Americas, H. amplexicaulis, is well known in other parts of the world as an introduced and invasive species.
Ischnodemus variegatus is a species of insect in the order of true bugs known by the common name myakka bug. It is native to Central and South America. It is also known as an introduced species in Florida in the United States.
Sporobolus michauxianus is a species of cordgrass known as prairie cordgrass, freshwater cordgrass, tall marshgrass, and sloughgrass. It is native to much of North America, including central and eastern Canada and most of the contiguous United States except for the southwestern and southeastern regions. Its distribution extends into Mexico. It is also present on other continents as an introduced species.
Setaria sphacelata is a tall African grass, also known as South African pigeon grass and African bristlegrass. It is native to tropical and subtropical Africa, and is extensively cultivated globally as a pasture grass and for cut fodder. This is a rhizomatous perennial grass producing flattened, hairless, blue-green stems up to 2 m tall. The inflorescence is a dense, narrow panicle of bristly, orange-tinged spikelets up to 25 cm long.
Sporobolus indicus is a species of grass known by the common name smut grass.
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Panicum repens is a species of grass known by many common names, including torpedo grass, creeping panic, panic rampant, couch panicum, wainaku grass, quack grass, dog-tooth grass, and bullet grass. Its exact native range is obscure. Sources suggest that the grass is native to "Africa and/or Asia", "Europe or Australia", "Eurasia", "Australia", "Europe, Asia, and Africa", or other specific regions, including the Mediterranean, Israel, and Argentina. It is present in many places as an introduced species and often a noxious weed. It has been called "one of the world's worst weeds."
Paspalum vaginatum is a species of grass known by many names, including seashore paspalum, biscuit grass, saltwater couch, silt grass, and swamp couch. It is native to the Americas, where it grows in tropical and subtropical regions. It is found throughout the other tropical areas of the world, where it is an introduced species and sometimes an invasive weed. It is also cultivated as a turfgrass in many places.
Leersia hexandra is a species of grass known by the common names southern cutgrass, clubhead cutgrass, and swamp rice grass. It has a pantropical distribution. It is also an introduced species in many regions, sometimes becoming invasive, and it is an agricultural weed of various crops, especially rice. It is also cultivated as a forage for livestock.
Brachiaria mutica is a species of grass known by the common names para grass, buffalo grass, Mauritius signal grass, pasto pare, malojilla, gramalote, parana, Carib grass, and Scotch grass. Despite its common name California grass, it does not occur in California; it is native to northern and central Africa and parts of the Middle East, where it is cultivated for fodder. It was introduced elsewhere and it is now cultivated throughout tropical regions of the world for this purpose.
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