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 morphological and molecular evidence has reseparated them. Some of the genera are nickel hyperaccumulators.

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, Eastern Europe, Siberia, the Russian Far East, Central Asia, the Caucasus, Western Asia, China, Mongolia and also Subarctic America.
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.

Taxonomy

Odontarrhena was a taxonomically difficult genus of the tribe Alysseae. However, recent morphological and molecular evidence clearly showed that Alyssum and Odontarrhena are monophyletic clades within the tribe Alysseae, deserving separate generic status.
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 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 and they only list Odontarrhena obovata as a known species.

Known species

The following list includes all species recognised by either Plants of [the World Online] or by BrassiBase. Of these, 80 species are recognised by both databases, with the remaining 16 accepted by only one of them.

Uses

About 48 members of the Odontarrhena species, are known to be nickel hyperaccumulators. The accumulation of nickel was first discovered in the Italian endemic Odontarrhena bertolonii (syn. Alyssum bertolonii 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.