ARABIDOPSIS (de Candolle) Heynhold in Holl & Heynhold, Fl. Sachsen 1: 538. 1842;

nom. cons.

Ihsan A. Al-Shehbaz

Tribe: Camelineae de Candolle, Mém. Mus. Hist. Nat. 7(1): 239. 1821.

Name derivation: From Arabis, a genus of Brassicaceae, and Greek opsis, aspect, in reference to resemblance to Arabis.

Type species: Arabidopsis thaliana (Linnaeus) Heynhold (based on Arabis thaliana Linnaeus); typ. Cons.

Cardaminopsis (C. A. Meyer) Hayek, Fl. Steiermark 1: 477. 1908. Type species: not designated.

Hylandra Á. Löve, Svensk Bot. Tidskr. 55: 211. 1961. Type species: H. suecica (E. M. Fries) A. Löve (based on Arabis suecica E. M. Fries).

     Herbs annual, biennial, or perennial with stolons or woody caudex. Trichomes simple mixed with stalked 1-3(or 4)-forked. Multicellular glands absent. Stems erect to ascending or decumbent, most frequently several from base, few branched above. Basal leaves petiolate, rosulate, simple, entire or toothed, sometimes lyrate to pinnately lobed, cauline leaves petiolate to subsessile and cuneate to attenuate at base, never auriculate or sagittate, entire, dentate, or rarely lyrate. Racemes few to several flowered, dense or lax, ebracteate, corymbose, elongated considerably in fruit; rachis straight; fruiting pedicels ascending to divaricate or slightly reflexed, persistent. Sepals oblong, free, erect to ascending, equal, base of inner pair slightly saccate or not. Petals white, pink, or purple, erect at base with flaring blade, longer than sepals; blade obovate to spatulate or oblanceolate, apex obtuse to emarginate; claw obscurely differentiated from blade or distinct, glabrous, entire. Stamens 6, exserted, erect, tetradynamous; filaments filiform, wingless, unappendaged, glabrousfree; anthers oblong, obtuse apex. Nectar glands confluent and subtending bases of all stamens; median nectaries sometimes distinct and not confluent. Ovules 15-80 per ovary; placentation parietal. Fruit dehiscent, capsular siliques, linear, terete or latiseptate, not inflated, unsegmented; valves papery, veinless or with a distinct midvein, glabrous, not keeled, smooth or somewhat torulose, wingless, unappendaged; gynophore to 1 mm; replum rounded, visible; septum complete, membranous, not veined; style obsolete to 1 mm, cylindric, persistent; stigma capitate, entire, unappendaged. Seeds uniseriate, wingless or margined, oblong to ellipsoid, plump or flattened; seed coat minutely reticulate, mucilaginous or not mucilaginous when wetted; cotyledons accumbent or rarley incumbent. 2n = 10, 16.

     Ten species: primarily in Europe, few extending into northern Asia and northern North America. Arabidopsis thaliana, a Eurasian weed naturalized worldwide, is the model organism in plant biology. For more information on the systematics and phylogeny of the species, see the referes below. For an up-to-date information on all other aspects of its biology, consult the NSF-funded web site TAIR (The Arabidopsis Information Resource) at http://arabidopsis.org.

References: Al-Shehbaz & O’Kane (2002), Al-Shehbaz et al. (1999), Beck et al. (2007, 2008), Clauss and Koch (2006), Kadota (2007), Koch et al. (1999, 2000, 2008), Kolník & Marhold (2006), Löve (1961), Meyerowitz (1989), Meyerowitz & Pruitt (1985), Mummenhoff & Hurka (1994, 1995), O’Kane & Al-Shehbaz (1997, 2003), O’Kane et al. (1997), Price et al. (1994), Warwick et al. (2006).

See the interactive key to species