Arabidopsis bactriana Belongs to Dielsiocharis (Brassicaceae)

2 Pages·2003·0.99 MB·English

by  Ihsan A Al-Shehbaz

Arabidopsis bactriana Belongs to Dielsiocharis (Brassicaceae)
Ihsan A. Al-Shehbaz
Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A.
Sabir ,/. Junussov
Institute of Botany, Tajik Academy of Sciences, Karamova Street 27,
Dushanbe 734017, Tajikistan
ABSTRACT. The Tajikistan endemic Arabidopsis base); entire, oblong, oblanceolate, or obovate, ro-
bactriana is transferred to Dielsiocharis, a genus sulale basal leaves attenuating to the petiole; leaf¬
previously recognized as monotypic. Detailed de¬ less stems; ebracteate, few- to several-flowered ra¬
scription of A. bactriana is provided, and a key cemes elongated in fruit; bright or pale yellow
distinguishing the two species of Dielsiocharis is petals 2.5-5 mm long; linear to oblong-linear, often
given. recurved, non-torulose, dehiscent, terete fruits; mi¬
Key words: Arabidopsis, Brassicaceae, Dielsi¬ nute, entire stigmas; and oblong, uniseriate seeds
ocharis, Taj i k i stan. with incumbent cotyledons (Hedge, 1968; Junus¬
sov, 1978).
During a visit to Dushanbe (Tajikistan) in 2002,
the first author had the chance to examine many
Dielsiocharis bactriana (Ovczinnikov A Junus¬
species of Brassicaceae at TAD. One of the species,
sov) Al-Shehbaz & Junussov, comb. nov. Bas-
previously placed in Arabidopsis (DC.) Heynhold,
ionym: Arabidopsis bactriana Ovczinnikov &
A. bactriana Ovczinnikov & Junussov, was studied
Junussov, FI. Tajikistan 5: 626. 1975. TYPE:
critically, anti the present paper deals with its prop¬
Tajikistan. Mt. kugi-Frusch, calcareous
er generic placement.
ground, 2800 m, 4 July 1956, D. N. Ovczin¬
Arabidopsis bactriana cannot be maintained in
nikov A M. S. Lazareva 4079 (holotype, TAD;
Arabidopsis because it is a pulvinate, scapose, ca-
isotype, TAD).
nescent perennial with almost exclusively dendritic
trichomes, leafless stems, pale yellow flowers, and Perennial herbs to 4 cm tall, pulvinate, scapose;
non-torulose fruits. As defined by O’Kane and Al- caudex woody, compact, covered with persistent
Shehbaz (1997), Arabidopsis consists of annual, bi¬ leaves of previous years. Leaves oblong-oblanceo-
ennial, or non-pulvinate, non-scapose, non-canes- late to obovate, 0.3—2 cm long, 1—3.5 mm wide,
cent perennials with simple and forked (never canescent, densely tomentose with stalked, den¬
dendritic) trichomes, leafy stems, white to lavender dritic trichomes, these with much longer stalks and
or rarely purple flowers, and torulose fruits. simple along petiolar base, base attenuate or cu-
Al-Shehbaz et al. (1999) excluded Arabidopsis neate, margin entire, apex obtuse. Cauline leaves
bactriana from Arabidopsis and, prior to the exam¬ absent. Raceme ebracteate, 3- to 6-flowered, elon¬
ination of the type material, suggested that the spe¬ gated in fruit. Sepals oblong, to 2 mm long, tomen¬
cies might belong to Crucihimalaya Al-Shehbaz et tose outside. Petals pale yellow, narrowly oblanceo¬
al. However, we now believe that the species should late, 2.5—3 mm long, apex rounded. Fruiting
be assigned to Dielsiocharis 0. E. Schulz, a genus pedicel slender, filiform, 5—10 mm long, sparsely
previously recognized by Schulz (1924. 1936) and tomentose. Ovules 34 to 40 per ovary'. Fruit linear,
Hedge (1968) as monotypic. terete, curved, not torulose, 7-15 X 0.7-1 mm;
In nearly all aspects of Arabidopsis bactriana, the valves glabrous, midvein absent or obscure; style
species is more closely related to Dielsiocharis kot- 0.1-0.5 mm long; stigma minute, entire. Seeds un¬
schyi (Boissier) 0. E. Schulz (northern Iran and ad¬ iseriate, oblong, brown, ca. 0.7 X 0.3 mm long;
jacent southern Turkmenistan) than to any other cotyledons incumbent.
species of the Brassicaceae. Both are densely caes-
pitose, pulvinate, tomentose, canescent, scapose Di elsiocharis bactriana is known thus far only
perennials with almost exclusively dendritic tri¬ from the type collection. It is easily distinguished
chomes (some simple trichomes at the petiolar from D. kotschyi by having fewer-flowered racemes.
Novon 13: 170-171. 2003.
Volume 13, Number 2 Al-Shehbaz & Junussov 171
2003 Arabidopsis bactriana transferred
glabrous fruit valves, and more ovules per ovary Literature Cited
(see key).
Al-Shehbaz, I. A., S. I,. O'Kane, Jr. & R. A. Price. 1999.
Generic placement of species excluded from Arabidopsis
Key to the Species of Dielsiocharis (Brassicaceae). Novon 9: 296—307.
Hedge, i. C. 1968. Sisymbrieae. In: K. H. Bechinger (ed¬
la. Fruit valves glabrous; racemes 3- to 6-flowered;
itor), FI. Iranica 57: 309-342. Akademische Druck-u.
ovules 34 to 40 per ovary.D. bactriana
lb. Fruit valves pubescent; racemes 10- to 20-flow- Verlagsanslalt, Graz-Austria.
ered; ovules 6 to 14 per ovary .D. kotschyi Junussov, S. 1978. Arabidopsis. In: P. N. Ovczinnikov (ed¬
itor), FI. Tajikistan 5: 44—51. USSR Academy of Sci¬
Acknowledgments. We are most grateful to Ac¬ ences, Leningrad.
ademician Hikmat Hisoriev, Director of the Insti¬ O’Kane, S. L., Jr. & I. A. Al-Shehbaz. 1997. A synopsis
tute of Botany of the Tajik Academy of Sciences, of Arabidopsis (Brassicaceae). Novon 7: 323—327.
Schulz, O. F. 1924. Cruciferae-Sisymbrieae. In: A. Engler
for his help during the 2002 visit of Al-Shehbaz to
(editor). Pflanzenreich IV. 105(Heft 86): 1—388. Verlag
TAD. We thank the National Geographic Society
von Wilhelm Engelmann, Leipzig.
(Grant N712I-01) for financial support. Victoria C. -. 1936. Crueiferae. In: A. Engler & K. Prantl (ed¬
Hollowell and Steve L. O'Kane, Jr., are thanked for itors), Nat. Pflanzenfam., ed. 2, 17B: 227—658. Verlag
their comments on the manuscript. von Wilhelm Engelmann, Leipzig.