Table Of ContentVolume 4 NOVON
Number 1
1994
Erysimum hedgeanum (Brassicaceae), a New Name Replacing
A rabid op s is erysimoide s
Ihsan A. Al-Shehbaz
Missouri Botanical Garden, l\0. Box 299, St. Louis, Missouri 63166-0299, U.S.A.
Abstract. Erysimum hedgeanum is a new name moides Karelin & Kirilov], TYPE; Saudi Ara¬
proposed to replace the later homonym that would bia. Hail to Jabbah road, Najud, between Qul-
result from the transfer of Arabidopsis erysimoides ban & Qana, sand dune, 900 m, 9 Mar. 1986,
to Erysimum. /. S. Collenetle 5713 (holotype, E; isotype, K).
During the past decade, increasing interest in Erysimum hedgeanum, which is named in honor
Arabidopsis resulted from the selection of one of of Ian G. Hedge (Royal Botanic Garden, Edinburgh),
its species, A. thaliana (L.) Heynhold, as the model an outstanding student of the Brassicaceae and the
flowering plant in basic and applied research in mo¬ senior author of Arabidopsis erysimoides, was orig¬
lecular genetics, developmental biology, plant phys¬ inally described in Arabidopsis mainly because its
iology, evolution, and other fields. The species has authors (Hedge & Tan, 1987: 202) concluded that
been recently named by Patrusky (1991) as the “A thorough herbarium and literature search in
“Drosophila botanica or the fruit fly of plant biol¬ Erysimum failed to reveal any species that was at
ogy,” and the outstanding features lor its selection all like the Arabian plant and our conclusion was
as a model organism have been covered by many that it could not be described as a new species in
reviews. The interested reader should consult Mey- Erysimum. Dr. Adoll Polatschek (Natural History
erowitz (1989) and references therein. Museum, Vienna) to whom we sent some material
Arabidopsis is one ol the most poorly defined for examination also concluded that it could not be
and artificially delimited genera of the Brassicaceae described as a new species in Erysimum. " However,
(Cruciferae) (Al-Shehbaz, 1988; Hedge & Tan, no reasons were given to justify its exclusion from
1987). Critical evaluation of the generic disposition Erysimum. The closely appressed medifixed tri¬
of species previously assigned to Arabidopsis is e-homes of E. hedgeanum are characteristic of many
needed. Biosystematic and phylogenetic studies of species of the genus, and the “unusual'’ combination
Arabidopsis and its generic relatives are well un¬ of linear-filiform leaves and reflexed fruits are indeed
derway at the Missouri Botanical Garden. The pres¬ found in several species of Erysimum. In fact, E.
ent paper deals with one of the problematic species, hedgeanum shares with E. sisymbrioides C. A.
which for the reasons below should be assigned to Meyer, another annual member of the genus, all the
the genus Erysimum. basic characters of indumentum, flower, and fruit
morphology that definitely support their placement
Erysimum hedgeanum Al-Shehbaz, nom. nov. in Erysimum. The characters of the leaves and fruits
Replaced name: Arabidopsis erysimoides used by Hedge & Tan (1987) to exclude the species
Hedge & Kit Tan, PI. Syst. Evol. 156: 202. from Erysimum can also be used to exclude it from
1987; not E. erysimoides (Karelin & Kirilov) Arabidopsis. In fact, no species of Arabidopsis or
Kuntze, Rev. Gen. 2; 933. 1891 [listed as E. its related genera have the trichome type ol E.
erysimodes but was based on Arabis erysi¬ hedgeanum. Medifixed appressed trichomes are
Novon 4: 1-2. 1994.
2 Novon
found in other genera of the Brassicaceae (e.g., (Price, 1987) and should therefore receive more
Lobularia Desvaux, Weberbauera Gilg & Mus- weight in the generic placement of this species.
chler, Farsetia Turra), but in all these cases either
all species of the genus have the same trichome type Acknowledgments. I am most grateful to the
or, in the case of Weberbauera (Al-Shehbaz, 1990), National Science Foundation for its support through
trends of the evolution to medifixed trichornes are the grant DEB-9208433. I am also thankful to the
found. directors and curators of the Koyal Botanic Gardens
In my opinion, every aspect of Erysimum hed- at Edinburgh and Kew' for the loans of the type
geanum supports its placement in Erysimum and collection of Arabidopsis erysimoides.
not in Arabidopsis. The absence of a very close
relative of this species does not justify its exclusion
Literature Cited
Irom Erysimum nor does it support its placement
Al-Shehbaz, I. A. 1988. The genera of Sisymbrieae
in a new genus. Furthermore, Hedge & Tan’s (1987)
(Cruciferae; Brassicaceae) in the southeastern United
argument that E. hedgeanum (as A. erysimoides) States. J. Arnold Arbor. 69: 213 237.
shares with Arabidopsis a similar habit, nonsaccate -. 1990. A revision of Weberbauera (Brassi-
sepals, small petals, incumbent cotyledons, and caeeae). J. Arnold Arbor. 71: 221-250.
Hedge, I. C. & K. Tan. 1987. Two remarkable new
readily dehiscent many-seeded fruits can be mis¬
Cruciferae from Saudi Arabia. PI. Syst. Evol. 156:
leading because this combination of characters is 197-206.
common elsewhere in the Brassicaceae, including Meyerowitz, E. M. 1989. Arabidopsis, a useful weed.
Erysimum, and must have evolved independently ' Cell 56: 263-269.
Patrusky, B. 1991. Drosophila botanica (the fruit fly
several times. The presence of appressed, medifixed,
of plant biology). Mosaic 22(2): 32-43.
2-branched trichornes oriented parallel to the long
Price, R. A. 1987. Systematics of the Erysimum cap-
axes of all exposed parts of the plant (excluding itatum alliance (Brassicaceae). Unpublished Ph.D.
petals and stamens) is a typical feature of Erysimum Dissertation, University of California, Berkeley.
