Erysimum hedgeanum (Brassicaceae), a New Name Replacing Arabidopsis erysimoides

Abstract

Erysimum hedgeanum is a new name proposed to replace the later homonym that would result from the transfer of Arabidopsis erysimoides to During the past decade, increasing interest in Arabidopsis resulted from the selection of one of its species, A. thaliana (L.) Heynhold, as the model flowering plant in basic and applied research in molecular genetics, developmental plant physiology, evolution, and other fields. The species has been recently named by Patrusky (1991) as the Drosophila botanica or the fruit fly of plant biology, and the outstanding features for its selection as a model organism have been covered by many reviews. The interested reader should consult Meyerowitz (1989) and references therein. Arabidopsis is one of the most poorly defined and artificially delimited genera of the Brassicaceae (Cruciferae) (Al-Shehbaz, 1988; Hedge & Tan, 1987). Critical evaluation of the generic disposition of species previously assigned to Arabidopsis is needed. Biosystematic and phylogenetic studies of Arabidopsis and its generic relatives are well underway at the Missouri Botanical Garden. The present paper deals with one of the problematic species, which for the reasons below should be assigned to the genus Erysimum hedgeanum Al-Shehbaz, nom. nov. Replaced name: Arabidopsis erysimoides Hedge & Kit Tan, P1. Syst. Evol. 156: 202. 1987; not E. erysimoides (Karelin & Kirilov) Kuntze, Rev. Gen. 2: 933. 1891 [listed as E. erysimodes but was based on Arabis erysimoides Karelin & Kirilov]. TYPE: Saudi Arabia. Hail to Jabbah road, Najud, between Qulban & Qana, sand dune, 900 m, 9 Mar. 1986, I. S. Collenette 5713 (holotype, E; isotype, K). Erysimum hedgeanum, which is named in honor of Ian C. Hedge (Royal Botanic Garden, Edinburgh), an outstanding student of the Brassicaceae and the senior author of Arabidopsis erysimoides, was originally described in Arabidopsis mainly because its authors (Hedge & Tan, 1987: 202) concluded that A thorough herbarium and literature search in Erysimum failed to reveal any species that was at all like the Arabian plant and our conclusion was that it could not be described as a new species in Dr. Adolf Polatschek (Natural History Museum, Vienna) to whom we sent some material for examination also concluded that it could not be described as a new species in Erysimum. However, no reasons were given to justify its exclusion from The closely appressed medifixed trichomes of E. hedgeanum are characteristic of many species of the genus, and the unusual combination of linear-filiform leaves and reflexed fruits are indeed found in several species of In fact, E. hedgeanum shares with E. sisymbrioides C. A. Meyer, another annual member of the genus, all the basic characters of indumentum, flower, and fruit morphology that definitely support their placement in The characters of the leaves and fruits used by Hedge & Tan (1987) to exclude the species from Erysimum can also be used to exclude it from Arabidopsis. In fact, no species of Arabidopsis or its related genera have the trichome type of E. hedgeanum. Medifixed appressed trichomes are