Atriplex

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Atriplex
Garden Orache (Atriplex hortensis)
From Sturm & Sturm (1796): Deutschlands Flora in Abbildungen.
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Core eudicots
Order: Caryophyllales
Family: Amaranthaceae
Subfamily: Chenopodioideae
Tribe: Atripliceae
Genus: Atriplex
L.
Species

About 250-300, see text

Synonyms

Blackiella Aellen
Cremnophyton
Haloxanthium Ulbr.
Morrisiella Aellen
Neopreissia Ulbr.
Obione Gaertn.
Pachypharynx Aellen
Senniella Aellen
Theleophyton (Hook.f.) Moq.

Atriplex (/ˈætrɨplɛks/[1]) is a plant genus of 250-300 species, known by the common names of saltbush and orache (or orach). It belongs to the subfamily Chenopodioideae of the family Amaranthaceae (which include the Chenopodiaceae of the Cronquist system). The genus is quite variable and widely distributed. It includes many desert and seashore plants and halophytes, as well as plants of moist environments. The generic name originated in Latin and was applied by Pliny the Elder to the edible oraches.[2] The name saltbush derives from the fact that the plants retain salt in their leaves, which makes them of great use in areas affected by soil salination.

Description[edit]

Atriplex patula, female flower with bracteoles and seed

The species in genus Atriplex are annual or perennial herbs, subshrubs, or shrubs. The plants are often covered with bladderlike hairs, that later collapse and form a silvery, scurfy or mealy surface, rarely with elongate trichomes. The alternate or rarely opposite leaves are petiolate or sessile, often persistent or tardily deciduous. The flat or slightly fleshy leaf blades are either entire, or serrate, or lobed and very variable in shape.[3][4]

The inflorescences consist of axillary or terminal spikes or spicate panicles, or axillary clusters of glomeruled flowers. The flowers are unisexual, some species are monoecious, others dioecious. Male flowers consist of 3-5 perianth lobes and 3-5 stamens. Female flowers are usually lacking a perianth, but are enclosed by 2 foliaceous bracteoles, and contain an ovary with a short style and 2 stigmas.[3][4]

In fruit, the bracteoles can enlarge, thicken or become appendaged. They enclose the fruit tightly, without becoming connate to it. The pericarp is adnate to the vertically orientated, flattened seed. The seed coat is thick, leathery or hardening. The annular embryo surrounds the perisperm.[3][4]

The chromosome base number is x = 9, except for Atriplex lanfrancoi, which is x=10.[5]

A few Atriplex species are C3-plants, but most species are C4-plants, with a characteristic leaf anatomy (kranz anatomy).[5]

Distribution and evolution[edit]

The genus Atriplex is distributed nearly worldwide from subtropical to temperate and to subarctic regions. Most species rich are Australia, North America, South America and Eurasia. Many species are halophytes and are adapted to dry environments with salty soils.[5]

The genus evolved in Middle Miocene, the C4-photosynthesis pathway developed about 14,1-10,9 million years ago, when the climate became increasingly dry. The genus diversified rapidly and spread over the continents. The C4Atriplex colonized North America probably from Eurasia during the Middle/Late Miocene, about 9,8-8,8 million years ago, and later spread to South America. Australia was colonized twice by two C4 lineages, one from Eurasia or America about 9,8-7,8 million years ago, and one from Central Asia about 6,3-4,8 million years ago. The last lineage diversified rapidly, and became the ancestor of most Australian Atriplex species.[5]

Ecology[edit]

Atriplex species are used as food plants by the larvae of some Lepidoptera species; see the list of Lepidoptera which feed on Atriplex. For spiders such as Phidippus californicus and other arthropods, saltbush plants offer opportunities to hide and hunt in habitat that is otherwise often quite barren.

Use by humans[edit]

Many species are edible. However, the favored species for human consumption is Garden Orache (A. hortensis). Use of Atriplex as food is known since at least the late Epipaleolithic (Mesolithic). The Ertebølle culture presumably used Common Orache (A. patula) as a vegetable (A. patula is attested as an archaeophyte in northern Europe). In the biblical Book of Job, mallûḥa (מַלּ֣וּחַ, probably Mediterranean Saltbush, A. halimus, the major culinary saltbush in the region) is mentioned as food eaten by social outcasts (Job 30:4[6]). Grey Saltbush (A. cinerea) is used as bushfood in Australia since prehistoric times. Chamiso (A. canescens) and Shadscale (A. confertifolia) were eaten by Native Americans, and Spearscale (A. hastata) was a food in rural Eurasia.

Meat from sheep which have grazed on saltbush has surprisingly high levels of vitamin E, is leaner and more hydrated than regular lamb and has consumer appeal equal to grain-fed lamb.[citation needed] The vitamin E levels could have animal health benefits while extending the shelf-life and maintaining the fresh red colour of saltbush lamb. This effect has been demonstrated for Old Man Saltbush (A. nummularia) and River Saltbush (A. amnicola). For reasons unknown, sheep seem to prefer the more fibrous, less nutritious River Saltbush.[7][8]

Saltbushes are also used as an ornamental plant in landscaping and can be used to prevent soil erosion in coastal areas. Old Man Saltbush has also been successfully used to rehabilitate old mining sites around Lightning Ridge (Australia).

Silvery Saltbush
Atriplex lentiformis
Old Man Saltbush
Atriplex nummularia

Systematics[edit]

The genus Atriplex was first described in 1753 by Carolus Linnaeus in Species Plantarum 2, p. 1052–1054.[9] The type species (lectotypus) is Atriplex hortensis.[10]

Atriplex is an extremely species rich genus and comprises about 250[4]-300[5] species. After phylogenetical research, Kadereit et al. (2010) excluded Halimione as a distinct sister genus. The remaining Atripex species were grouped into several clades, that mostly are not identical with the traditional sections:[5]

  • Atriplex lanfrancoi/cana-Clade:
    • Atriplex lanfrancoi (Brullo & Pavone) G. Kadereit et Sukhor. (Syn.: Cremnophyton lanfrancoi Brullo & Pavone): endemic in Malta and Gozo.
    • Atriplex cana C.A. Mey.: from Eastern European Russia to Western China

Selected species not yet investigated phylogenetically:

Excluded species:

References[edit]

  1. ^ Sunset Western Garden Book, 1995:606–607
  2. ^ Quattrocchi, Umberto (2000). CRC World Dictionary of Plant Names. I: A-C. CRC Press. p. 232. ISBN 978-0-8493-2675-2. 
  3. ^ a b c Stanley L. Welsh: Atriplex - online, In: Flora of North America Editorial Committee (ed.): Flora of North America North of Mexico, Volume 4: Magnoliophyta: Caryophyllidae, part 1., Oxford University Press, New York. 2003, ISBN 0-19-517389-9.
  4. ^ a b c d Gelin Zhu, Sergei L. Mosyakin & Steven E. Clemants: Chenopodiaceae: Atriplex - online, In: Wu Zhengyi, Peter H. Raven, Deyuan Hong (ed.): Flora of China, Volume 5: Ulmaceae through Basellaceae., Science Press und Missouri Botanical Garden Press, Beijing und St. Louis, 2003, ISBN 1-930723-27-X.
  5. ^ a b c d e f g h Gudrun Kadereit, Evgeny V. Mavrodiev, Elizabeth H. Zacharias & Alexander P. Sukhorukov: Molecular phylogeny of Atripliceae (Chenopodioideae, Chenopodiaceae): Implications for systematics, biogeography, flower and fruit evolution, and the origin of C4 Photosynthesis. - American Journal of Botany 97(10): 1664-1687, 2010.
  6. ^ Mistranslated as "mallows" in the King James Bible and as Nesseln (nettles) in the Luther Bible
  7. ^ Norman, Hayley C.; Freind, Colby; Masters, David G.; Rintoul, Allan J.; Dynes, Robyn A. & Williams, Ian H. (2004): Variation within and between two saltbush species in plant composition and subsequent selection by sheep. Aust. J. Agr. Res. 55(9): 999–1007. doi:10.1071/AR04031 (HTML abstract)
  8. ^ Pearce, Kelly & Jacob, Robin (2004): Saltbush lifts sheep meat vitamin content. Farming Ahead 153(October): 63. PDF fulltext
  9. ^ Species Plantarum at BHL
  10. ^ Atriplex at Tropicos, accessed 2013-07-11
  11. ^ Tasmanian name, also transcribed trucanini, trucaninny, trugannini, trugernanna, etc. The plant was the namesake for Truganini, among the last of her people.
  12. ^ a b Elizabeth H. Zacharias, Bruce G. Baldwin (2010): A Molecular Phylogeny of North American Atripliceae (Chenopodiaceae), with Implications for Floral and Photosynthetic Pathway Evolution. In: Systematic Botany 35(4), p.839-857. doi:10.1600/036364410X539907
  • Davidson, Alan (1999): Orach. In: Oxford Companion to Food: 556. ISBN 0-19-211579-0
  • Everitt, J.H.; Lonard, R.L.; Little, C.R. (2007). Weeds in South Texas and Northern Mexico. Lubbock: Texas Tech University Press.  ISBN 0-89672-614-2

External links[edit]