Volume 7 NOVON Number 2 1997 Arabidopsis gamosepala and A. tuemurnica Belong to Neotorularia (Brassicaceae) Ihsan A. Al-Shehbaz Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A. Steve L. O'Kane, Jr. Department of Biology, University of Northern Iowa, Cedar Falls, Iowa 50614-0421, U.S.A. Abstract. The new combination Neotorularia having mucilaginous instead of non-mucilaginous gamosepala is proposed. Arabidopsis tuemurnica is seeds. However, this feature is unreliable, and reduced to synonymy of N. humilis. The limits of many genera of the Brassicaceae include species Arabidopsis and Neotorularia are discussed. with or without seed mucilage (Vaughan & White- house, 1971). The most reliable characters for the separation of these genera are the trichome and Although Arabidopsis thaliana has become the fruit types. Neotorularia has distinctly torulose plant of choice in molecular, developmental, phys¬ fruits with pubescent valves, and the trichomes are iological, genetic, and related studies, little is primarily few to several branched. In contrast, Ar¬ known about its immediate relatives, and the limits abidopsis has non-torulose glabrous fruits, and the of Arabidopsis remain controversial (Al-Shehbaz, trichomes are simple mixed primarily with 2-forked 1988; Price et al., 1994). For the past few years, ones. Both Arabidopsis gamosepala and A. tuemur¬ the present authors have been working on the elu¬ nica have the typical features of Neotorularia men¬ cidation of the generic boundaries of Arabidopsis, tioned above. and some of the species previously assigned to this A synopsis of Neotorularia is being carried out genus have already been transferred to other genera by the authors, and it is estimated that the genus (Al-Shehbaz, 1994; Al-Shehbaz & O’Kane, 1995). includes 25—30 species. Because the completion of The present paper deals with two such controversial the revision will take some time, the following no- species. menelatural adjustments are proposed to make On the basis of molecular studies (O’Kane et al., them available for some of the checklists and floras 1997), Arabidopsis gamosepala Hedge (endemic to in progress, especially the forthcoming treatment of Afghanistan) and A. tuemurnica Kuan & An (en¬ the Brassicaceae for the Flora of China. demic to China) form with the widespread Neoto¬ rularia torulosa (Desfontaines) Hedge & Leonard Neotorularia gamosepala (Hedge) Al-Shehbaz & (China west into western Russia, the Middle East, O’Kane, comb. nov. Basionym: Arabidopsis ga¬ and North Africa) a well-defined clade distinctly mosepala Hedge, FI. Iran. 57: 334. 1968. unrelated to that including Arabidopsis. The evi¬ TYPE: Afghanistan. Munjan: above Anjuman dence from morphology (see below) fully supports valley, near Anjuman, 3100 m, 14 Aug. 1965, the molecular data to include these two species in Podlech 12379 (holotype, M; isotype, W). Neotorularia. Schulz (1924) separated Arabidopsis from Toru- Hedge (1968) indicated that Arabidopsis gamo¬ laria (now Neotorularia) primarily on the basis of sepala has no clear ally in Arabidopsis and that it Novon 7: 93-94. 1997. 94 No von is anomalous in the genus for lac king the median ican Braya needs a comprehensive study, and some nectar glands, a feature characteristic of Neotoru- of its species may well prove to be Neotorularia, a laria. The species appears to be most closely re¬ genus up to this study not yet recognized in North lated to N. torulosa, from which it is readily distin¬ America. guished in being a perennial with a gamosepalous Acknowledgments. We are grateful to Barbara calyx. Neotorularia torulosa is an annual with free Schaal (Washington University, St. Louis) for pro¬ sepals. viding the space and facilities in her lab to conduct molecular studies on various genera of the Brassi- INeotoruluriu liuiiiilis (C. A. Meyer) Hedge & Le¬ caceae. The senior author gratefully acknowledges onard, Bull. Jard. Bot. Belg. 56: 394. 1986. the generous financial support of the National Sci¬ Sisymbrium humile C. A. Meyer, in Ledebour, ence Foundation (grant DEB-9208433) and the Na¬ Icon. PI. Ross. 2: 16. 1830. TYPE: Altai, C. tional Geographic Society (grant 5068-93) to con¬ A. Meyer s.n. (holotype, LE). duct fieldwork in Europe and Asia. Arabidopsis litemarnica Kuan & An, Hull. Bot. Lab. North- East. Forest. Inst. 8: 44. 1980. Syn. nov. TYPE: Chi¬ Literature Cited na. Xinjiang: Wen-su Xian, Tno-mn-er-feng, 2400 rn, Abbe, E. C. 1948. Braya in Boreal eastern America. 24 June 1977, Tuo-mu-er-feng Expedition 770084 Rhodora 50: 1-15. (holotype, PE, listed as IIP; isotype, BJM. listed as Al-Shehbaz, I. A. 1988. The genera of Sisymbrieae (Cru- HM). eiferae; Brassieaceae) in the southeastern United States. J. Arnold Arbor. 69: 213-237. In their original description of Arabidopsis tue- -. 1994. Erysimum hedgeanum (Brassieaceae), a marnica, Kuan and An (1980) compared the spe¬ new name replacing Arabidopsis erysimoides. Novon 4: cies with A. thaliana and indicated that it is an 1-2. annual differing primarily in the basal leaves. How¬ -. & S. L. O’Kane, Jr. 1995. Placement of Arabi¬ dopsis parvula in Thellungiella (Brassieaceae). Novon ever, an examination of the holotype of the former 5: 309-310. reveals that it is a short-lived perennial clearly un¬ Harris, J. C. 1985. A Revision of the Genus Braya (Cru- related to A. thaliana, especially in fruit and tri- ciferae) in North America. Unpublished Ph.D. thesis, chome characters. In fac t, the1 plant is indistin¬ University of Alberta, Canada. guishable from the highly variable Neotorularia Hedge, 1. C. 1968. Arabidopsis. In: K. H. Reehinger (ed¬ itor). FI. Iran. 57: 328-334. humilis, a species widespread in northern North Kuan, K. C. & Z. X. An. 1980. Taxa nova eruciferarum America (Alaska and Canadian Arctic south to Col¬ sinicarum. Bull. Bot. Lab. North-East. Forest. Inst. 8: orado and east to Vermont) and northern Asia (Rus¬ 39-46. sia and China south to the Himalayas and west to O’Kane, S. I... Jr., B. A. Schaal <X I. A. Al-Shehbaz. 1996 [1997|. The origins of Arabidopsis suerica (Brassica- Afghanistan, Pakistan, and Central Asia). North eeae) as indicated by nuclear rDNA sequences. Syst. American authors (e.g., Abbe, 1948; Harris, 1985; Bot. vol. 21 (in press). Rollins, 1993) treated N. humilis in Braya. How¬ Price, B. A., J. I). Palmer & I. A. Al-Shehbaz. 1994. ever, the molecular evidence (O’Kane et al., 1997; Systematic relationships of Arabidopsis-. A molecular O’Kane, unpublished), as well as the c ritical and morphological perspective. In: E. M. Meyerowitz & C. B. Sommerville (editors), Arabidopsis. Cold Springs morphological comparison of the species with its Harbor Laboratory Press, New' York. Asian representatives and other Neotorularia spe¬ Rollins, R. C. 1993. The Cruciferae of Continental North cies, clearly support the placement of this species America. Stanford Univ. Press, Stanford, California. in Neotorularia. Unfortunately, all studies of the Schulz, O. E. 1924. Cruciferae—Sisymbrieae. In: A. En- gler, Pflanzenr. IV 105(Heft 86): 1—388. North American Braya completely ignored the Vaughan, J. G. & J. M. Whitehouse. 1971. Seed structure Asian members and gave no reference to Neotoru¬ and the taxonomy ol the Cruciferae. Bot. J. Linn. Soc. laria or Torularia. In our opinion, the North Amer¬ 64: 383-409.