Phylogenetic analyses, biogeography, morphology, and ecology confirm that Helenium scaposum is a distinct species belonging to genus Helenium. Within Helenium, it appears that H. scaposum is most closely related to members of Helenium sect. Leptopoda. The morphological resemblance of H. scaposum to H. drummondii, H. pinnatifidum, and H. vernale justifies further study to better understand relationships among these species.

Based on evidence supporting the recognition of Tetraneuris as a genus separate from Hymenoxys, Hymenoxys argentea var. thoreauensis is basionym of a new combination, Tetraneuris argentea var. thoreauensis.

Hymenoxys ambigens var. wagneri is a new variety endemic to the Dragoon Mountains of Cochise County, Arizona.

Hymenoxys subg. Rydbergia comprises H. brandegeei, H. grandiflora, and H. insignis. The treatment includes a discussion of the original circumscription of the taxa, the description of the genus Rydbergia to accommodate H. brandegeei and H. grandiflora, the eventual placement of Rydbergia within Hymenoxys as a subgenus, and relationships of the three taxa to one another and to other taxa of Hymenoxys. The treatment also includes synonymies, descriptions, and range maps for each of the species, and lectotypification of Actinella brandegeei.

Tetraneuris is recognized as a genus separate from Hymenoxys and a taxonomic treatment is presented for the 14 taxa recognized as constituting Tetraneuris: T. acaulis var. acaulis, T. acaulis var. arizonica, T. acaulis var. caespitosa, T. acaulis var. epunctata, T. argentea, T. herbacea, T. ivesiana., T. linearifolia var. linearifolia, T. linearifolia var. arenicola, T. scaposa var. scaposa, T. scaposa var. argyrocaulon, T. torreyana, T. turneri, and T. verdiensis. The revision includes synonymies, typifications, descriptions, discussions, and range maps for each of the accepted species.

Six compounds from the aerial parts of the Argentinean plant Hymenoxys robusta (Rusby) Parker were isolated and their structures elucidated using extensive spectroscopic analyses. These compounds comprise two inositol derivatives and four 3,4-seco-pseudoguaianolides, including vermeerin. Bioactivity assays of these compounds against bacterial and fungal pathogens showed that only vermeerin possessed antimicrobial activity specific against Staphylococcus aureus, and showed no toxicity when exposed to human-derived macrophages.

Hymenoxys (Helenieae, Tetraneurinae) is composed of 28 taxa distributed in 8 subgenera: 1) subg. Hymenoxys, 2) subg. Dugaldia, 3) subg. Macdougalia, 4) subg. Phileozera, 5) subg. Picradenia, 6) subg. Picradeniella, 7) subg. Plummera, and 8) subg. Rydbergia. Eleven taxa comprise Hymenoxys subg. Picradenia.

Generic delimitation in the Hymenoxys complex has long been problematic. One taxonomic extreme would recognize only Hymenoxys, whereas the other would split the obviously related taxa into as many as eight genera. This study examined restriction site variation in both cpDNA and nrDNA in the Hymenoxys complex. Fifty-six populations representing 21 species (four with two varieties each) and six of the eight possible genera were analyzed using 21 enzymes, which resulted in the detection of 358 restriction site changes of which 171 were potentially phylogenetically informative. Wagner parsimony using synapomorphic characters generated 26,600 equally parsimonious trees of 223 steps with a consistency index of 0.76 and a retention index of 0.98. Bootstrap analysis indicated that the major clades were strongly supported. The DNA tree supports the recognition of Tetraneuris as a genus separate from Hymenoxys, and the inclusion in Hymenoxys of taxa that at times have been split into the genera Dugaldia, Macdougalia, Phileozera, Picradenia, and Plummera.

All currently recognized taxa from the genera Amblyolepis (one species), Dugaldia (three species), Hymenoxys (22 taxa in 21 species), Macdougalia (one species), Plateilema (one species), Plummera (two species) and Tetraneuris (15 taxa in eight species) were examined for chemical constituents accumulated in capitate glandular trichomes. Fifty-nine high pressure liquid chromatography (HPLC) peaks were detected, over 70% of which could be tentatively assigned to known compounds of the sesquiterpene lactone, monoterpene and inositol types. This is the first report of sesquiterpene lactone glycosides, monoterpene glycosides and a myoinositol derivative in capitate glandular trichomes. Apart from Amblyolepis and Plateilema, which did not afford analyzable glandular trichomes, sesquiterpene lactones of the pseudoguaianolide type were present in all species, and guaianolides were found in all but two, Hymenoxys anthemoides and H. chrysanthemoides. Compound patterns of the Hymenoxys, Plummera, Dugaldia and Macdougalia species were very similar to one another, but they differed from those of Hymenoxys texana and all taxa of Tetraneuris, which lacked modified pseudoguaianolides (secohelenanolides), but contained monoterpene glycosides. Taxonomic implications of compound patterns in the species examined includes: (1) incorporation of Dugaldia, Plummera and Macdougalia into a broader concept of Hymenoxys; and (2) recognition of Tetraneuris as a distinct genus. Hymenoxys texana requires further investigation since its morphology is typical of Hymenoxys, but its chemistry is typical of Tetraneuris.

Aerial parts of a new variety of Tetraneuris linearifolia, var. arenicola afforded, in addition to known helenanolides and germacranolides, a new guaianolide, 10 new esterified glucopyranosides of 9-hydroxy-γ-geraniol, two palmitates of lupeol derivatives, a mixture of glucopyranoside p-coumarates and eight flavonoids including the new 5,8,3′-trimethoxy-5,7,4′,5′-tetrahydroxyflavone.

Six guaianolides, seven pseudoguaianolides and an aliphatic lactone were isolated from Hymenoxys scaposa var. villosa. Six of these compounds, villosin A, villosin B, 4-acetyl-chamissonolide, 2-desacetyl-2-isobutyryl- chamissonolide, 2-desoxypleniradin and 2-desoxy-14-acetoxy-pleniradin, are reported for the first time.

AbstractDie Verbindungen (I) und (II) werden isoliert und strukturell sichergestellt.

Fifteen flavonoids were identified in the eight taxa of Clematis subsection Viornae. Flavonols, flavones, and C-glycosyl flavones were present. The compounds were based primarily on luteolin, apigenin, quercetin, and kaempferol. The systematic significance of the distribution of these compounds among the taxa is discussed.