Tuesday, April 7, 2009

Arabidopsis Thaliana – Mouse-ear cress

Arabidopsis thaliana
The story of bitter cress continues with Arabidopsis thaliana – (thale cress, mouse-ear cress) – a plant in the mustard - Brassicaceae - family. This plant’s small size, the small size of its genome, and the relatively short time from germination to mature seed facilitate plant genetic studies. It is called a model organism and it is the drosophila of the plant world. Arabidopsis is the first plant to have it genome sequenced. In fact you can look it up at the Arabidopsis Information Resource site. This plant must be pretty special since it has its own web site. The site is definitely not for the layperson, but there is a nice history page about Arabidopsis there.

In my Plant ID class we keyed out the plant in Hitchcock and Cronquist (with a little help from the instructor). Though non-native, Arabidopsis appears in H&C on page 152. We went off track trying to identify if the seeds were biseriate (in two rows) or uniseriate (page 147). We initially chose biseriate and were wrong.
Arabidopsis thaliana in Hitchcock and Cronquist
The genus and species name? From the calflora.net site:
  • Arabidop'sis: from the Greek for "resembling Arabis" (ref. genus Arabidopsis)
  • Ar'abis: a Greek word used for "mustard" or "cress," and the Greek word for Arabia, perhaps referring to the ability of these plants to grow in rocky or sandy soils (?) (ref. genus Arabis)
  • thalia'na: after Johannes Thal (1542-1583), who discovered this species in the Harz Mountains and originally called it Pilosella siliquosa. Its current name was finally settled on in his honor in 1842 (ref. Arabidopsis thaliana)

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