Sinosenecio newcombei (Asteraceae: Senecioneae): A New Combination for a North American Plant in an Asiatic Genus John P. Janovec and Theodore M. Barkley Herbarium, Division of Biology, Kansas State University, Manhattan, Kansas 66506, U.S.A. Abstract. The plant long called Senecio new¬ many of them have been long-recognized as sec¬ combei Greene is a distinctive endemic of the tions or other infrageneric groups within Senecio s.l. Queen Charlotte Islands, B.C., Canada. Microchar¬ New data derived from morphological analyses and acters, cytology, and gross morphology indicate its from biochemical/genetic investigations, plus the affinities with the tussilaginoid group of the Sene¬ rigor of modem phylogenetic theory, combine to fa¬ cioneae and with the East Asian genus Sinosenecio. vor narrower generic concepts. Recognition of The new nomenclatural combination is made: Si¬ smaller, segregate genera was promoted in the nosenecio newcombei (Greene) J. P. Janovec & T. M. 1970s by Robinson, often in collaboration with Barkley. Brettell, in a series of papers centered upon the plants of southern North America and eastern Asia (see Barkley, 1985b, and Bremer, 1994, for cita¬ Work on generic treatments for the Flora of North tions). Nordenstam (1977, 1978) accepted a series America North of Mexico project has drawn our of segregate genera in a world-wide catalog pre¬ attention to the problematic Senecio newcombei sented in connection with the symposium on the Greene. The entity was described from a collection Biology and Chemistry of the Compositae, at the made by C. F. Newcombe in 1897 at the site of a University of Reading, U.K., in the summer of Norwegian fishing camp just north of Kaisun on the 1975. Jeffrey treated the traditional Senecio, s.l., as west coast of Moresby Island, Queen Charlotte Is¬ a series of segregate genera in several papers, cul¬ lands, B.C., Canada, and was named in honor of minating in his generic catalog of Senecioneae (Jef¬ the collector (Greene, 1897). Subsequent studies frey, 1992). Bremer also treated Senecio, s.l., as nu¬ have agreed that the entity is restricted to the merous segregates in his monumental review of the Queen Charlotte Islands, where it occurs on open, Asteraceae of the world (Bremer, 1994). He provid¬ rocky, and boggy sites throughout the western ed cladograms, based on morphological characters, coastlands and on the heathy rock-talus slopes of of the evolutionary lineages within the Senecioneae, the Takakia Lake alpine region (Barkley, 1962, as he saw them, and he stressed the morphological 1978, 1988; Calder & Taylor, 1968; Douglas, distinctions between the subtribes Senecioninae 1982). Greene (1897) treated the entity as a Senecio and Tussilagininae, i.e., the senecionoid and tus¬ because of its evident gross morphology, and Bark¬ silaginoid lineages. (The tussilaginoids were called ley (1962) included it within the Aurei species- “cacalioids” and “tephroseroids” in the older lit¬ group as a matter of convenience. Calder and Tay¬ erature.) Barkley et al. (in press) summarized the lor (1968) recognized that S. newcombei did not fit distinctions among the segregates in these two lin¬ comfortably among the Aurei but suggested that it eages in Mexico and Central America and offered might be related to the aureoid S. porteri Greene, a distinctive monocephalous alpine species of the a justification for regarding them as genera. The senecionoid lineage is characterized by hav¬ Colorado Rocky Mountains and apparently the Wal¬ ing style branches with separate stigmatic lines, up¬ lowa Mountains of northeastern Oregon. In 1988, Barkley excluded S. newcombei from the aureoid per stamen filaments with swollen collars (“balus- complex and suggested that it might have Asiatic terform”), anthers often with thickenings in the affinities. lateral walls of the endothecial cells, and chromo¬ Since then, generic concepts within the Seneci¬ some numbers based on x = 10 or 20 or numbers oneae have undergone revision. As recently as derived therefrom. In the tussilaginoid lineage, the 1985, Barkley could argue for maintaining Senecio stigmatic surface is entire or nearly so across the as a single, diverse genus, and this notion reflected inner face of the style branch, the upper stamen American floristic traditions (Barkley, 1985a, b). filaments are cylindrical, the anthers often have Detailed studies, however, have made a compelling thickenings in the transverse walls of the endo¬ case for treating the various segregates as genera; thecial cells, and the chromosome numbers are Novon 6: 265-267. 1996. 266 Novon based mostly on x = 30 or numbers derived there¬ More likely, S. newcombei is a locally adapted relict from, including numbers down to x = 24, presum¬ of some past distributional event. ably via aneuploid reduction (Bremer, 1994). The The following new combination is made here: nature of the microcharacters in the Senecioneae is illustrated by photographs in Nordenstam (1978), Sinosenecio newcombei (Greene) J. P. Janovec Jeffrey & Chen (1984), and Wetter (1983). & T. M. Barkley, comb. nov. Basionym: Senecio Specimens of Sirwsenecio newcombei were bor¬ newcombei Greene, Pittonia 3: 249. 1897. rowed for study (cited below), and slides were made Type: Canada. British Columbia: Queen Char¬ to observe microcharacters. The techniques for mi¬ lotte Islands, June 1897, Newcombe s.n. (US). crocharacter analyses were learned by the first au¬ Specimens examined. CANADA. British Columbia: thor from H. Robinson at the Smithsonian Insitu- McClinton Bay, Graham Island, 18 June 1957, Colder, tion, and they are similar to those of Wetter (1983). Savile & Taylor 21605 (NY); Kootenay Inlet, Moresby Is¬ Sirwsenecio newcombei uniformly has the entire land, 21 July 1964, Colder & Taylor 36195 (NY); Kait- stigmatic areas and the cylindrical stamen filaments goro, 1903, Newcombe s.n. (MO-photo); Canoe Passage, 26 July 1910, Spreadborough 91260 ex Herb. Geol. Survey of the tussalaginoid lineage and also has thicken¬ of Canada (MO). ings in the transverse walls of the endothecial cells, i.e., the thickenings are “polarized.” In aspect and Acknowledgments. We thank C. Jeffrey, R. R. Kowal, B. Nordenstam, and H. Robinson for shar¬ in these microcharacters, it clearly resembles the ing their knowledge and enthusiasm for the Sene¬ Asiatic tussilaginoid segregate genus Sirwsenecio B. cioneae. The administration of the Smithsonian In¬ Nordenstam. The chromosome number for this spe¬ stitution provided the fellowship that permitted the cies is re = 24, which is known from several counts first author to study for the summer of 1995 in the (Taylor & Mulligan, 1968). This number occurs in U.S. National Herbarium, under the guidance of H. some other tussilaginoid species but is apparently Robinson and V. Funk. We also thank the curators not known among senecionoid species. of the above noted herbaria for lending specimens The aureoid assemblage of Senecio is senecion¬ and otherwise permitting us to study their collec¬ oid in microcharacters, but it has a distinctive chro¬ tions. This is contribution No. 96-294-J from the mosome number of re = 22 or 23 or polyploid de¬ Kansas Agricultural Experiment Station, Manhat¬ rivatives thereof. Moreover, it is distinguished by tan. having pollen walls of a helianthoid rather than a senecioid structure (Bain & Walker, 1995). The au¬ Literature Cited reoid assemblage is now recognized as the segre¬ gate genus Packera Love & Love, and it definitely Bain, J. & J. Walker. 1995. A comparison of the pollen wall ultrastructure of aureoid and non-aureoid Senecio does not include Sirwsenecio newcombei. species (Asteraceae) in North America. PI. Syst. Evol. Specimens referable to Sirwsenecio were sur¬ 195: 199-207. veyed by the first author in the herbarium of The Barkley, T. M. 1962. A revision of Senecio aureus Linn, New York Botanical Garden (NY) and by both au¬ and allied species. Trans. Kansas Acad. Sci. 65: 318- 408. thors in the herbarium of the Missouri Botanical -. 1978. Senecio. In N. Amer. Flora II. 10: 50- Garden (MO), and we conclude that Sirwsenecio 139. newcombei is comfortably similar to the Asiatic spe¬ -. 1985a. Generic boundaries in the Senecioneae. cies of Sirwsenecio. Sirwsenecio newcombei resem¬ Taxon 34: 17-21. -. 1985b. Infrageneric groups in Senecio, s.l., and bles S. homogyniphyllus (Cumm.) B. Nordenstam, Cacalia, s.l. (Asteraceae: Senecioneae) in Mexico and which was illustrated in Nordenstam (1978), and Central America. Brittonia 37: 211—218. several of the species illustrated by Jeffrey and -. 1988. Variation among the aureoid senecios of Chen (1984) in their account of the Sirwsenecio in North America: A geohistorical interpretation. Bot. Rev. 54: 82-106. Eastern Asia. Sirwsenecio newcombei appears to fall -, B. L. Clark & A. M. Funston. In press. The among the species referable to their subsection Ma- segregate genera of Senecio, s.l., and Cacalia, s.l., (As¬ darogyne. teraceae: Senecioneae) in Mexico and Central America. The recognition that a distinctive and highly re¬ In: D. J. N. Hind et al. (editors). Proceedings of the International Copmpositae Conference, Kew, 1994. stricted North American plant belongs to an oth¬ Royal Botanic Gardens, Kew. erwise Asiatic group raises biogeographic questions Bremer, K. 1994. Asteraceae: Cladistics & Classification. that are beyond the scope of this paper. It is re¬ Timber Press, Portland. motely possible that the American plants derive Calder, J. A. & R. L. Taylor. 1968. Flora of the Queen Charlotte Islands, Part 1. Research Branch, Cana • from a relatively recent introduction, but S. new¬ Dept. Agric. Monogr. 4, part 1. combei is distinctive and is not known in Asia. Douglas, G. W. 1982. The sunflower family (Asteraceae) Volume 6, Number 3 Janovec & Barkley 267 1996 Sinosenecio newcombei from North America in British Columbia, Vol. 1—Senecioneae. Occas. Pap. beae—Systematic review. In: V. H. Heywood et al. (ed¬ British Columbia Provincial Mus., no. 23. itors), The Biology and Chemistry of the Compositae, Greene, E. L. 1897. Senecio newcombei. Pittonia 3: 249. Vol. 2. Academic Press, London. Jeffrey, C. 1992. The tribe Senecioneae (Compositae) in -. 1978. Taxonomic notes on the tribe Senecioneae the Mascarene Islands with an annotated world check¬ (Compositae). Opera Bot. 44: 1-84. Taylor, R. L. & G. A. Mulligan. 1968. Flora of the Queen list of the genera in the tribe: Notes on Compositae VI. Charlotte Islands, Part 2, Cytological aspects of the vas¬ Kew Bull. 47: 49-109. cular plants. Res. Branch, Canad. Dept. Agric., Monogr. -& Y-L. Chen. 1984. Taxonomic studies on the 4, part 2. tribe Senecioneae (Compositae) in eastern Asia. Kew Wetter, M. A. 1983. Micromorphological characters and Bull. 39: 205-446. generic delimitation of some New World Senecioneae Nordenstam, B. 1977 (publ. 1978). Senecioneae and Lia- (Asteraceae). Brittonia 35: 1—22.