Odontarrhena

Odontarrhena is a large genus of flowering plants in the family Brassicaceae. They were originally a separate genus and then were amalgamated into the Alyssum genus, but then morphological and molecular evidence has reseperated them. Some of the genera are nickel (Ni) hyperaccumulators (a plant capable of growing in soil or water with very high concentrations of metals).

Description
It is similar in habit to Alyssum and has small yellow flowers, except that it has a suborbicular pouch and one seeded cells. The plants are characterised by inflorescences that are usually compound, subumbellate racemes. There is a single ovule per loculus, and the fruit valves are at most only slightly inflated.

Range
Its widespread native range is from temperate Eurasia to subarctic America. It is found in Europe (within Albania, Bulgaria, Corsica, Crete, Czechoslovakia, East Aegean Islands, France, Greece, Hungary, Italy, Romania, Sardina, Sicily, Switzerland and Yugoslavia), Eastern Europe (within Central European Russia, Crimea, East European Russia, North European Russia, South European Russia and Ukraine), Siberia (within Altai, Buryatiya, Chita Oblast, Irkutsk Oblast, Krasnoyarsk Krai, Tuva, West Siberia and Yakutskiya), the Russian Far East (within Amur Oblast, Khabarovsk Krai and Magadan Oblast), Central Asia (within Kazakhstan and Turkmenistan), the Caucasus (North Caucasus and Transcaucasus), Western Asia (Afghanistan, Cyprus, Iran, Iraq, Lebanon, Palestine, Saudi Arabia, Syria and Turkey), China (Inner Mongolia, Manchuria and Xinjiang), Mongolia and also Subarctic America (within Alaska, Northwest Territories and the Yukon).

The Balkan Peninsula is a major diversity center. Greece has the largest number of species; next, Albania is known to have 7 species. It is also found on the serpentine soils of Lesbos Island (in Greece).

Taxonomy
Odontarrhena was a taxonomically difficult genus of the tribe Alysseae. However, recent morphological and molecular evidence (DNA analysis) clearly showed that Alyssum and Odontarrhena are monophyletic clades within the tribe Alysseae, deserving separate generic status (Warwick et al. 2008; Cecchi et al. 2010; Rešetnik et al. 2013; Li et al. 2015).

The genus name of Odontarrhena is derived from two Greek words; odous meaning tooth and arrhen meaning male. It was first described and published by Carl Anton von Meyer in Flora Altaica (edited by Carl Friedrich von Ledebour) Vol.3 on page 58 in 1831.

The genus is recognized by the United States Department of Agriculture and the Agricultural Research Service, but they still list it as synonym of Alyssum L. and they only list Odontarrhena obovata C. A. Mey. as a known species.

Known species
The following list includes all species recognised by either Plants of the World Online (as of January 2022) or by BrassiBase (version 1.3, June 2020). Of these, 80 species are recognised by both databases, with the remaining 16 accepted by only one of them (this is indicated in each entry).
 * Odontarrhena akamasica
 * Odontarrhena albiflora
 * Odontarrhena alpestris
 * Odontarrhena americana ; only in Plants of the World Online; in BrassiBase it is a synonym of Odontarrhena obovata
 * Odontarrhena anatolica
 * Odontarrhena argentea
 * Odontarrhena baldaccii ; only in Plants of the World Online
 * Odontarrhena bertolonii
 * Odontarrhena borzaeana ; accepted in BrassiBase; in Plants of the World Online it is a synonym of Odontarrhena obtusifolia
 * Odontarrhena bracteata
 * Odontarrhena caliacrae ; only in Plants of the World Online; in BrassiBase it is a synonym of Odontarrhena tortuosa subsp. caliacrae
 * Odontarrhena callichroa
 * Odontarrhena carica
 * Odontarrhena cassia
 * Odontarrhena chalcidica
 * Odontarrhena chondrogyna
 * Odontarrhena cilicica
 * Odontarrhena condensata
 * Odontarrhena constellata
 * Odontarrhena corsica
 * Odontarrhena corymbosoidea
 * Odontarrhena crenulata
 * Odontarrhena cyprica
 * Odontarrhena davisiana
 * Odontarrhena debarensis
 * Odontarrhena decipiens ; according to Plants of the World Online; on BrassiBase it is Odontarrhena lurensis
 * Odontarrhena diffusa ; accepted in BrassiBase; in Plants of the World Online it is a synonym of Odontarrhena argentea
 * Odontarrhena discolor
 * Odontarrhena dubertretii
 * Odontarrhena dudleyi
 * Odontarrhena elatior ; accepted in BrassiBase; in Plants of the World Online it is a synonym of Odontarrhena chalcidica
 * Odontarrhena eriophylla
 * Odontarrhena euboea
 * Odontarrhena fallacina ; accepted in BrassiBase; in Plants of the World Online it is a synonym of Odontarrhena heldreichii
 * Odontarrhena fedtschenkoana
 * Odontarrhena filiformis
 * Odontarrhena floribunda
 * Odontarrhena fragillima
 * Odontarrhena gehamensis
 * Odontarrhena gevgelicensis
 * Odontarrhena giosnana
 * Odontarrhena haradjianii
 * Odontarrhena haussknechtii
 * Odontarrhena heldreichii
 * Odontarrhena huber-morathii
 * Odontarrhena inflata
 * Odontarrhena kavadarcensis
 * Odontarrhena kurdica
 * Odontarrhena lanigera
 * Odontarrhena lesbiaca
 * Odontarrhena libanotica
 * Odontarrhena litvinovii
 * Odontarrhena lurensis ; according to BrassiBase; in Plants of the World Online it is Odontarrhena decipiens
 * Odontarrhena markgrafii ; accepted in BrassiBase; in Plants of the World Online it is a synonym of Odontarrhena chalcidica
 * Odontarrhena masmenaea
 * Odontarrhena metajnae
 * Odontarrhena moravensis ; only in Plants of the World Online
 * Odontarrhena mozaffarianii ; only in Plants of the World Online
 * Odontarrhena mughlaei
 * Odontarrhena muralis
 * Odontarrhena nebrodensis
 * Odontarrhena obovata
 * Odontarrhena obtusifolia
 * Odontarrhena orbelica
 * Odontarrhena oxycarpa
 * Odontarrhena pateri
 * Odontarrhena peltarioidea
 * Odontarrhena penjwinensis
 * Odontarrhena pinifolia
 * Odontarrhena polyclada
 * Odontarrhena pterocarpa
 * Odontarrhena pugiostyla
 * Odontarrhena rigida ; only in Plants of the World Online
 * Odontarrhena robertiana
 * Odontarrhena samarifera
 * Odontarrhena samia
 * Odontarrhena schirwanica ; accepted in BrassiBase; in Plants of the World Online it is a synonym of Odontarrhena tortuosa subsp. tortuosa
 * Odontarrhena serpentina
 * Odontarrhena serpentinicola
 * Odontarrhena serpyllifolia ; according to BrassiBase; in Plants of the World Online it is Alyssum serpyllifolium
 * Odontarrhena sibirica
 * Odontarrhena singarensis
 * Odontarrhena skopjensis
 * Odontarrhena smolikana
 * Odontarrhena stipitata
 * Odontarrhena stridii ; only in Plants of the World Online
 * Odontarrhena subalpina
 * Odontarrhena subspinosa
 * Odontarrhena syriaca
 * Odontarrhena szarabiaca
 * Odontarrhena tavolarae
 * Odontarrhena tortuosa
 * Odontarrhena trapeziformis
 * Odontarrhena troodi
 * Odontarrhena turgida
 * Odontarrhena virgata

Uses
About 48 members of the Odontarrhena species, are known to be nickel (Ni) hyperaccumulators (a plant capable of growing in soil or water with very high concentrations of metals). The accumulation of nickel was first discovered in the Italian endemic Odontarrhena bertolonii (Desv.) Jord. and Fourr. (syn. Alyssum bertolonii Desv. by Minguzzi and Vergnano in 1948, Of the 168 or so species of Alyssum, 45 species were determined to be hyperaccumulators of nickel, all from the Odontarrhena section. The metal is found in the roots, stem, leaves and flowers of the plant.

Other sources

 * Cecchi, L., Colzi, I., Coppi, A., Gonnelli, C. & Selvi, F. (2013) Diversity and biogeography of Ni-hyperaccumulators of Alyssum section Odontarrhena (Brassicaceae) in the central western Mediterranean: evidence from karyology, morphology and DNA sequence data. Botanical journal of the Linnaean Society 173: 269–289.
 * Nyárády, E.J. (1929a) [“1928”] Studiu preliminar asupra unor specii de Alyssum din secţia Odontarrhena. Vorstudium über einige Arten der Section Odontarrhena der Gattung Alyssum (Forsetzung). Buletinul Gradinii Botanice si al Muzeului Botanic dela Universitatea din Cluj 8 (2–4): 152–156.