Creeping Saltbush

Atriplex semibaccata, commonly known as Australian saltbush, berry saltbush, or creeping saltbush, is a species of flowering plant in the family Amaranthaceae and is endemic to Australia. It is a perennial herb native to Western Australia, South Australia, Queensland and New South Wales, but has been introduced into other states and to overseas countries. It flowers and fruits in spring, and propagates from seed when the fruit splits open. This species of saltbush is adapted to inconsistent rainfall, temperature and humidity extremes and to poor soil. It is used for rehabilitation, medicine, as a cover crop and for fodder. Its introduction to other countries has had an environmental and economic impact on them.

Description

''Atriplex semibaccata'' is a taproot perennial herb, that has prostrated and decumbent characteristics. Native to Australia and widespread in all mainland Australian states, ''A. semibaccata'' thrives in harsh and saline conditions. ''A. semibaccata'' is often mat-forming or semi-erect and can grow 40–80 cm tall, spanning a diameter of 1.5-2m. Its slender branches arise from a woody taproot.

Leaves are white scruffy, subsessile (small stalk) and are spatulate or obovate (oblong or elliptic) when the plant is young. Leaves develop a green to grey-green colour, with a length of 5-30mm and a width of 2-9mm, where the base is tapered and tip obtuse. Leaves are thin, oblong-elliptic, obtuse and have short petiolate (1–2 cm). Stamen, Staminate flowers are tiny, terminal and 1.5mm wide, whereas Glossary of botanical terms, pistillate flowers cluster distally from leaves. ''A. semibaccata is'' monoecious.

Fruiting bracteoles are red or orange when mature, as well as having a convex and Rhombus, rhombic shape (diamond like appearance). Fruits are Succulent plant, succulent, united at base, margin toothed, sessile and are a length of 4-6mm.Heuzé V., Thiollet H., Tran G., 2016. Creeping saltbush (Atriplex semibaccata). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/183

''A. semibaccata'' is Plant propagation, seed propagated and seeds are List of polymorphisms#Heterospermy, dimorphic. Black seeds are 1.5-1.7mm, while brown seeds are 2mm in size. It can be used as fodder and is useful for Land degradation, degraded or salt affected land. Optimal conditions for habitat, include dry/subtropical climate and direct sunlight. ''A. semibaccata'' has an all-year season of interest and a Hardiness (plants), plant hardiness zone of 4. ''A. semibaccata'' requires light wikt:hydration#Noun, hydration in soil that is either clay, loam, peat, sand or silt as well as a soil pH that is PH, neutral.

Taxonomy and naming

''Atriplex semibaccata'' was first formally described in 1810 by Robert Brown (botanist, born 1773), Robert Brown in his ''Prodromus Florae Novae Hollandiae et Insulae Van Diemen''. The species is classified in the Amaranthaceae family and Chenopodiaceae subfamily, along with other Halophyte, halophytic plants (salt-tolerant) species. ''A. semibaccata'' has several reported varieties such as var. ''melanocarpa'', var. ''biformis,'' var. ''microcarpa'' var. ''Atriplex gracilis, gracilis'' and var. ''appendiculata''. These variations include the Plant morphology, morphological differences within this species.

Australia's Flora of Australia, native range is centred on bracteoles, which are the succulent fruits of ''A. semibaccata.'' There are two forms of ''A. semibaccata'' in Australia. In Western Australia and southern arid areas are home to rhomboid and succulent bracteoles, whereas slim dry and deltoid shaped bracteoles are found in Queensland and New South Wales. ''A. semibaccata'' Hybrid (biology), hybridises with Atriplex spinibractea, where both species subside in New South Wales. This formed the variant, known as A. neurivalvis in North Queensland, northern Queensland, where succulence is not apparent in its bracteoles.

Genetic variability analysis with the use of molecular markers has investigated ''A. semibaccata'' and other species of the genus ''Atriplex''. Phylogenetic analysis has confirmed a deviation from all other tested species (''Atriplex halimus, A. halimus, Atriplex amnicola, A. amnicola'', ''Atriplex lentiformis, A. lentiformis'', ''Atriplex canescens, A. canescens,'' ''A. undulata'' and ''Atriplex nummularia, A. nummularia'').  ''A. semibaccata'' is distinguished as one of two major groups that are least similar to the other species.

The common names for ''A. semibaccata'' include the ''Australia saltbush.'' It is also commonly called ''Australian saltweed, creeping saltbush'' and ''berry saltbush''. This is one of many ''Atriplex'' species native to Australia and is referenced widely in North America. The genus name Atriplex has Latin origins from the ‘''atriplexum''’, which has been derived from the Ancient greek language, Greek word ‘''astraphaxes''’, which translates to "''saltbush''" or "''orach''". The species epithet ‘''semibaccata''’ is derived from the Latin word ‘''semi''’ which translates to "half", while ‘''baccata''’ means "bearing berries".

Distribution and habitat

This species of saltbush is endemic to Australia and is native to Western Australia, South Australia, Queensland and New South Wales, but has become Naturalisation (biology), naturalised in the Australian Capital Territory, on Norfolk Island and possibly Tasmania. It has also been introduced to North and South America, North Africa, the Horn of Africa, the Middle East, Arabian Peninsula, Asia, and the Mediterranean region.  A. ''semibaccata'' was introduced to different regions worldwide as a drought and Halophyte, salt tolerant Fodder, fodder crop. Similarly, A. ''semibaccata'' was introduced in Tasmania for grazing purposes. Located in heavy soil that is slightly Soil salinity, saline, in woodland that is close to salt lakes, and is usually an Invasive species, invader of disturbed areas. First reported distribution was in California in 1901 as a livestock forage in alkaline regions. Seeds were soon after distributed (1916) and by 1940, A. ''semibaccata'' inhabited South Coast (California), southern coast regions and irregularly inland. Optimal conditions for habitat, include dry/Subtropics, subtropical climate and direct sunlight.

Ecology

Reproductive biology

''A. semibaccata'' reproduces by Germination, seed propagation. This appears when the fruiting bracteoles split when ripe and dry, exposing an individual seed. The seed is with Radicle, ascending radicle. ''A. semibaccata'' is self-compatible and Anemophily, wind pollinated''.'' Plant reproductive morphology, Male flowers occur as small glomerules in distal axils, while Plant reproductive morphology, female flowers appear in scattered Axillary bud, axillary clusters. Seed persistence in soil and germination conditions are unknown. ''A. semibaccata'' does not obtain dormancy when germination rates are high.

In Australia, ''A. semibaccata'' flowers and fruits in Spring (season), spring and summer, however flowering is prolonged in Western Australia. ''A. semibaccata'' in the Northern Hemisphere, northern hemisphere (United States, USA) typically flowers in spring (March–May), summer (June–August) and early winter (December–February).

Physiology and phenology

The development of C4 photosynthesis, C₄ photosynthesis has played a role in the evolutionary success of the Atriplex genus. Various C₄ Chenopodiaceae plants differ from the Kranz Anatomy, Kranz anatomy of Atriplex, which includes a layer of bundle sheath cells surrounding the vascular bundle, as well as radially arranged palisade cells, with little variation in C₄ leaf types. Depending on the immediate environmental conditions, ''A. semibaccata'' demonstrates the ability to adapt. This relates to environmental conditions such as air temperature, soil moisture, salinity and evaporation.

Greater exposure to a saline environment, induces a Abiotic stress, salt stress response which displays a decrease number of chloroplasts in chlorenchyma and bundle sheath cells, as well as a decreased root diameter, leaf size, Stromal cell, leaf stromal conductance and the net leaf photosynthetic rate. Higher saline exposure increases Gas exchange, intracellular CO₂ concentration and the number of stomata per unit leaf area.

During winter, ''A. semibaccata'' becomes dormant, whereas other ''Atriplex'' species maintain function. Low and inconsistent rainfall, varying temperatures, humidity and poor soil are contributing factors that involve ''A. semibaccata'' to adapt.

Cultivation

Environmental requirements

''A. semibaccata'' is native to Australia, however it is not located in Tropics, tropical and Humidity, humid regions such as North Queensland, Northern Queensland. It is a drought tolerant species of Subtropics, subtropical arid and Semi-arid climate, semi-arid regions. A region with a mean annual rainfall of 250-900mm is optimal for ''A. semibaccata''. It is a low spreading and deep-rooted Subshrub, sub-shrub that does not require much soil moisture. Sun exposed regions are an optimal condition for growth.  ''A. semibaccata'' is winter tolerant and can survive a minimum air temperature of -5 °C. ''A. semibaccata'' is salt-laden wind tolerant and has been indicated as an environmental advantage against plants that are distributed along coastal regions. Additionally, Soil salinity, saline soil allows for rapid and more profuse seed germination. This is a competitive advantage, against native species worldwide. ''A.'' ''semibaccata'' has a high degree of salt tolerance (9-16 dS/m) and grows in soil that is exposed to light and is acidic. ''A. semibaccata'' grows in various soil types, including clay loams, sandy loams and waterlogged environments.

Movement and dispersal

Natural dispersion of ''A. semibaccata'' are over short distances as seeds are found under remnant and understorey plants. Animal dispersion expands the distance covered of ''A. semibaccata''. The red fruiting bracteoles of ''A. semibaccata'' are Succulent plant, succulent and are attractive to herbivore species. Species that eat the fruiting bracteoles are responsible for animal dispersion and spread the seed of A. semibaccata. ''A. semibaccata'' seeds have been found in the digestive tract of  reptiles, birds and foxes in California, United States, USA.  Accidental introduction of ''A. semibaccata'' is a result of relocating hay and other Fodder, fodder crops. ''A. semibaccata'' was introduced internationally to various countries, to acquire the drought and saline resistant properties that allow for use as a fodder and Groundcover, ground cover.  ''A. semibaccata'' is intentionally dispersed for its uses.

Uses

Cover crop

In its native range of Australia, ''A. semibaccata'' is used in agroforestry to improve the performance and profitability of vineyards. ''A. semibaccata'' has been introduced to regions with reduced water availability due to drought and increased temperatures, as a sustainable cover crop that deters potential Pest (organism), pest species. Native perennial cover crops such as ''A. semibaccata'' can increase the abundance of Symbiosis, symbiotic invertebrates that can improve pest control and limit the need of synthetic pest controls.

Rehabilitation

''A. semibaccata'' has been used for Regenerative agriculture, regenerative purposes, where it has been planted to restore mine spoils. ''A. semibaccata'' is adaptive to the saline and drought conditions of Tailings, mining waste and exhibits germination among these regions. ''A. semibaccata'' has also been used for landscaping purposes and as ground cover to control soil and Soil erosion, erosion.  ''A. semibaccata'' is an effective weed control in Road verge, verges, roundabouts and nature strips. Additional uses of ''A. semibaccata'' includes land reclamation without the need for saline water Irrigation, irrigation systems and restoring bare patches of ground.

Fodder/ Animal feed

''A. semibaccata'' is used as saltland pasture and produces fodder for grazing animals when sources of paddock feed are limited. This can improve production from saltland sites, reduce salt movement and stabilise soil structure. ''A. semibaccata'' is a readily grazed ''Atriplex'' saltbush, which provides a more diverse diet and primary fodder/ animal feed. The high salt content in Leaf, foliage reduces the use of ''A. semibaccata'' as a food source if availability of drinking water for livestock is not adequate. ''A. semibaccata'' is Palatability, palatable when young, contains a low energy value and is a source of Protein (nutrient), crude protein. Additional food supplements and adequate drinking water are necessary for livestock.

Medicinal

''A. semibaccata'' essential oils contain compounds with Antibiotic, antibacterial and antioxidant properties. The essential oils of ''A. semibaccata'' are moderately Synergy, synergistic with gentamicin, which is an antibiotic that is used to treat several Pathogenic bacteria, bacterial infections. ''A. semibaccata'' is suitable for revegetation of marginal lands, with the use of its Biomass (ecology), biomass as an essential oil for the control of microbial infections. Additionally, Alcohol (chemistry), alcohol extracts from ''A. semibaccata'', such as scopoletin, coumarin, scopolin, Umbelliferone, umbelliferorne, 7-methoxy coumarin, phenolic acid and P-Coumaric acid, P-coumaric acid has antibacterial activity. Isolated compounds from ''A. semibaccata'', such as compounds tyramine and lignanamide exhibit Cytotoxicity, cytotoxic activity against the Cell proliferation, proliferation of leukemia lymphoblasts (CCRF-CEM) cells.

Environmental impact

''A. semibaccata'' is grown and dispersed over short distances. This creates a dense Fire retardant, fire-retardant groundcover, ground cover that displaces Native species, native plant species. ''A. semibaccata'' is identified as an Invasive species, invasive species by the United States Fish and Wildlife Service, US Fish and Wildlife service and is known to affect endangered species such as Panicum niihauense (critically endangered), Verbesina dissita and Sesbania tomentosa. Scaevola coriacea and Sesbania tomentosa are native and endangered grass species of Hawaii, United States, USA.  Scaevola coriacea is found in three naturally occurring populations and Sesbania tomentosa is located on the island of Molokai. In California, USA, ''A. semibaccata'' competes with native plants such as Verbesina dissita for space, shade, water and light. ''A. semibaccata'' creates an ecological shift that is caused by competition for resources, shading, ecosystem change and habitat alteration.

''A. semibaccata'' enhances biodiversity through Biological pest control, biological control. Agroecosystems that involve ''A. semibaccata'' increase the abundance of invertebrates that assist in pest control as well as an increased range of Predation, predators and parasitoids. ''A. semibaccata'' acts as a cover crop that provides shelter for various invertebrates, this increases biodiversity and bioactivity. This provides the environment for natural breakdown of organic material, aeration and Nutrient cycle, nutrient cycling that keeps ''A. semibaccata'' and surrounding vegetation healthy. Additionally, this abundant soil diversity supports pest predators that prevent harmful organisms from over populating. This prevents the destruction of crops. ''A. semibaccata'' improves the quality and structure of soil, suppresses weeds and contributes to pest management.
File:Starr 031007-2051 Atriplex semibaccata.jpg, Invasive growth in Kahoolawe, Hawaii
File:Atriplex semibaccata by Scott Zona - 003.jpg, Invasive growth in the Canary Islands, Spain
File:Starr 081230-0706 Atriplex semibaccata.jpg, Invasive growth of in Kahoolawe, Hawaii

Economic impact

The economic impact of ''A. semibaccata'' is positive in regions where it is not Invasive species, invasive. Benefits that have a positive economic effect include its value in rehabilitation, Medicinal plants, medicinal properties as well as food and cover cropper. The negative economic impact is generated by its Invasive species, invasiveness that endangers native species, causes a change in ecological and alters the surrounding biodiversity. This requires physical and chemical control processes that can be laborious and require economic expenditure. Control chemicals for ''A. semibaccata'' involve herbicides, such as dicamba, dicamba/MCPA amine, 2,4-Dichlorophenoxyacetic acid, 2,4-D and picloram/2,4-Dichlorophenoxyacetic acid, 2,4-D.  To physically remove ''A. semibaccata'', hand pulling is an effective method due to its small size. To physically control ''A. semibaccata'', it must be uprooted prior to seed production. Site revision is required to remove plants arising from residual seed pools.

References

External links

FAO:''Atriplex semibaccata''USDA Plants Profile: ''Atriplex semibaccata'' NSW Flora Online: ''Atriplex semibaccata''Online Field Guide to Common Saltmarsh Plants of Queensland

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Atriplex, semibaccata
Caryophyllales of Australia
Flora of New South Wales
Flora of the Northern Territory
Flora of South Australia
Flora of Victoria (state)
Eudicots of Western Australia
Taxa named by Robert Brown (botanist, born 1773)
Forages
Edible fruits