Billie L. Turner

Chromosome numbers in the Compositae-III. Certain Mexican species

SummaryChromosome counts for 26 species of Mexican composites are reported for the first time. These include first reports for 10 genera (Piqueria, Dicranocarpus, Flourensia, Montanoa, Sabazia, Zaluzania, Florestina, Loxothysanus,Palafoxia, and Sartwellia).Particularly noteworthy is the diploid chromosome count forSabazia humilis (n = 4), the lowest count so far reported for the subtribe Verbesininae. Chromosome numbers and morphological features indicate that the generaSartwellia andFlaveria are perhaps best placed with or close to the genusHaplöesthes. Various other realignments and/or relationships are tentatively suggested.

Chromosome counts of Latin American Compositae

Chromosome numbers are reported for 111 species of Compositae from Argentina, Chile, Costa Rica, Guatemala, Mexico, Paraguay, and Peru. These include first reports for 46 taxa, including 3 genera (Kyrsteniopsis K. & R.: N = 10, Eupatoriastrum Greenman: N = 16, and Piptothrix B. L. Robins.: N = ca. 17). The new combination, Decachaeta pyramidalis (B. L. Robins.) Sundberg, Cowan, & Turner, based on Piqueria pyramidalis B. L. Robins. is proposed.

Phylogenetic and Evolutionary Implications of Interspecific Chloroplast DNA Variation in Krigia (Asteraceae-Lactuceae)

Chloroplast DNA restriction site and length variation was examined among 12 taxa of Krigia, using 34 restriction endonucleases, filter hybridization experiments, and comparative mapping procedures. A total of 252 restriction site mutations was detected, 159 of which were phylogenetically informative. The resulting phylogenetic trees correlated well with cytological and morphological data. The two sects. Krigia and Cymbia differed by at least 73 restriction site mutations. Most species within each section were characterized by many restriction site changes. Interspecific sequence divergence in Krigia was much higher than in any other previously studied genus of the Asteraceae and was comparable to the high levels of divergence found in genera of other angiosperm families. Relative rates of chloroplast DNA evolution in Krigia were significantly different among the various chromosome number groups, resulting in the rejection of a molecular clock. However, a molecular clock could not be rejected within each chromosome number group. Different regions of the chloroplast genome also showed extremely different frequencies of mutations and four hotspot areas were identified. The areas occurred in long spacer regions between gene coding sequences. Furthermore, most of the homoplasy and length variation also occurred within these hotspots. Chloroplast DNA trees were consistent with the hypothesis that an ancient allopolyploid event between species with low chromosome base numbers, followed by subsequent aneuploid reduction, resulted in K. wrightii with n = 9. The results also suggest that x = 5 is the probable ancestral base number for the genus and that aneuploid reduction is the major mode of chromosome number change in Krigia and related genera.

A preliminary cladistic analysis of the genus Vernonia (Vernonieae: Asteraceae)

A cladistic study of the sections and subsections of the genus Vernonia was performed using 32 characters. The resulting cladograms indicate that New and Old World taxa are largely distinct, but differences in topology of equally parsimonious trees indicate that the level and position of connections is unclear. The yellow-flowered trinervate-leaved species of Madagascar separate out as distinct from other Old World taxa as do the large-headed leafy-bracted species of the New World Leiboldia group. Problems are encountered with the placement of the New World subsect. Eremosis/Critoniopsis and the Old World subsectt. Strobocalyx and Urceolatae. Our analyses support the overall synoptic treatment of Jones and Jeffrey, however there are areas of phylogenetic and taxonomic difficulty which need further study. Other non-morphological characters are required to resolve problematic relationships and provide a taxonomic framework reflective of phylogenetic relationships.

New species and combinations in Vernonia sections Leiboldia and Lepidonia (Asteraceae), with a revisional conspectus of the groups

The wholly North American sectionLeiboldia ofVernonia as revised by Jones (1979) included six species. The present treatment recognizes only three species inLeiboldia, including one newly described from recent collections. The remainder of what Jones consideredLeiboldia has been transferred into a new sect.Lepidonia (Blake) Turner which was first proposed as a monotypic genus. A key to the two sections and 10 species is provided along with an account of their interrelationships. Morphological evidence suggests that sect.Lepidonia is one of the more primitive sections ofVernonia, being as close to certain African sections as they are to the mostly American sect.Vernonia. Consideration is given to the phyletic significance and generic value of receptacular pales in the Vernonieae from which it is concluded that these have persisted in three or more quite unrelated lines of this tribe and undue weight should not be accorded these in generic considerations. Consequently, the paleaceous, monotypic generaLepidonia andBolanosa are sunk into synonymy underVernonia, the former as a distinct section, the latter into the sect.Vernonia.

Phylogenetic Relationships within the Tageteae (Asteraceae) Based on Nuclear Ribosomal ITS and Chloroplast ndhF Gene Sequences

Abstract Tageteae consist of approximately 216 New World species with a center of diversity in the Mexican highlands. The present study uses DNA sequences of the internal transcribed spacer region of nuclear ribosomal DNA and the 3′ end of the ndhF gene from the chloroplast to assess phylogenetic relationships within the tribe. Although trees from the two molecular makers are not completely congruent, both data sets provide support for the recognition of 21 genera of Tageteae. The combined data set generates a well-resolved tree with strong support for the monophyly of all but three genera. Tagetes is paraphyletic because Adenopappus and Vilobia are nested within the genus. Porophyllum is shown to be polyphyletic and P. tridentatum and P. crassifolium are recognized as belonging to a newly described genus Bajacalia. Two new combinations, B. tridentata and B. crassifolia, are proposed. Additionally, a new species Bajacalia moranii B. L. Turner, is described. The other species of Porophyllum examined are nested within or formed a sister group to Pectis. Dyssodia sensu lato is not monophyletic and its segregate genera should be recognized. The DNA phylogenies also support the transfer of Dyssodia jelskii into Schizotrichia, resulting in the new combination S. jelskii. The recognition of Pectis as a separate subtribe is also not supported. The lack of support for subtribal groupings and the small size of the Tageteae argue against formal recognition of subtribes. Chromosomal and biogeographic data correspond well with the combined molecular phylogeny. The phylogeny suggests that the Tageteae probably originated in Mexico and that there have been at least three independent introductions into South America. Chromosome numbers are quite variable within the tribe but are consistent within clades. The ancestral base chromosome number for the Tageteae is most likely x = 12 and there have been several episodes of aneuploid reduction in the evolution of the tribe. Communicating Editor: John V. Freudenstein

Meiotic chromosome counts for 12 species of texas compositae

SummaryChromosome counts for 10 taxa of Texas Compositae are presented for the first time. These include first reports for the following genera:Chrysopsis (x = 5),Bahia (x = 12),Amblyolepis (x = 19) andTetragonotheca (x = 17). Meiotic chromosome counts from prophase material ofChrysopsis pilosa showed 3 bivalents and an apparent ring of 4. Meiosis in species of the remaining genera appeared completely normal. When appropriate, this chromosomal information has been related to taxonomic problems.

Nutlet sculpturing inScutellaria sect.Resinosa (Lamiaceae) and its taxonomic utility

Nutlet sculpturing of 22 taxa ofScutellaria sect.Resinosa, representing 18 of its 19 species, and the monotypic genusSalazaria was studied by scanning electron microscopy (SEM). The nutlets of sect.Resinosa, while remarkably variable among themselves, differed from hypothetically closely related sections in lacking circumferential banding and sessile glands. Species could be grouped by surface sculpturing into seemingly meaningful phenetic clusters.Scutellaria potosina var.platyphylla was sufficiently distinct micromorphically so as to be elevated to specific status asScutellaria platyphylla comb. and stat. nov. The significance of nutlet microcharacters within sect.Resinosa is discussed, especially as compared to closely related sections. The genusSalazaria had nutlet sculpturing quite different from all taxa belonging to sect.Resinosa.

Taxonomy ofNeurolaena (Asteraceae-Heliantheae)

A taxonomic treatment of the tropical genusNeurolaena (tribeHeliantheae, subtribeGalinsoginae) is rendered. Ten species are recognized: the widespread, annual, weedy,N. lobata and nine relatively rare, relictual, shrubby or small tree species, mostly restricted to southern Mexico and Central America. Distributional maps, key to species, and complete synonymy are presented. A chromosomal and chemical review is also provided.

Pseudoguaianolides and sesquiterpene glucoside from Gaillardia coahuilensis

Abstract From the aerial parts of Gaillardia coahuilensis , one secopseudoguaianolide, 12 pseudoguaianolides and one acyclic sesquiterpene glucoside, named gaillardoside, were isolated. Four of the compounds were previously unreported. This is the first isolation of a glycoside from the genus Gaillardia . Structures of all the compounds were elucidated by the spectral data including 2D COSY, 1 H- 13 C correlation spectroscopy and some chemical transformations.