Chromosome numbers and other cytogenetic data were determined from microsporocytes in 316 collections including 13 tribes of Compositae, mostly from Africa, Australia, Mexico, Central America, and South America. First reports are provided for 66 species and the genera Cassinia (2n ≈ 14(II)), Feldstonia (2n = 11(II)), Gochnatia (2n ≈ 23(II)), and Pseudoconyza (n = 10). In addition, new chromosome numbers are established at the generic level in Acourtia, Calea, Craspedia, Gnaphalium, Helipterum, Liabum, Leucheria, Smallanthus, Trixis, and Viguiera and at the specific level in 13 additional species.

A brief review is offered of major chromosome number variations in the Senecioneae based on recent delimitations of the tribe. An additional 78 chromosome reports are provided, including 19 new reports for species, with confirmed or expanded base numbers for the genera Gynoxys (x = 40), Lasiocephalus (x = 20), Pentacalia (x = 20, ca. 50), and Jessea (x = ca. 50). The base number for the tribe is x = 10, which is found in various multiples. The Blennospermatinae are one of the most distinct groups with a base of x = 9, considered an aneuploid reduction from x = 10. A new subtribe, Abrotanellinae, is established for the southern South American and southwest Pacific genus Abrotanella, which also has x = 9 and has often been placed in the Blennospermatinae. Numbers based on x = 30 and aneuploid reductions are found in the Tussilagininae, in many Australian Senecio, and in the Macaronesian Pericallis of the Senecioninae. The origin of such numbers is discussed. An anomalous North American group of Senecio (Packera) has variable numbers mostly near n = 23. Most Western Hemisphere Senecioninae have numbers of n = 20 or multiples thereof, with higher numbers in many Andean groups. Numbers of n = 10 or lower are mostly restricted to the Eastern Hemisphere, and groups like Emilia have recently dispersed from that area. Occurrences of n = 5 in Emilia, n = 10 in some American and Australian Senecio, and n = 14-16 in some tussilaginoids are considered as reductions.

The investigation of two Bejaranoa species from South America yielded, in addition to known sesquiterpene lactones and some other widespread metabolites, six new furanoheliangolides and a new pyranoheliangolide.

Reports of 68 new chromosome counts attributed to 53 species from 25 genera of Eupatorieae of the Asteraceae, based mostly on determinations of mitotic materials, include first counts for 2 genera (Acanthostyles and Lepidesmia) and 14 species and new reports for 8 species. B chromosomes are reported for 4 genera and 12 species. Karyotype analyses made on 20 species of Eupatorieae and one species of Heliantheae showed that total karyotypic lengths of the taxa with n = 16-19 of helianthoid and eupatorioid taxa are comparable to those of some eupatorioid taxa with n = 10. This is contrary to the previous hypothesis that the higher chromosome numbers n = 16-19 were derived from n = 10 by polyploidization followed by dysploid loss. Cytological data supplement and are consistent with the following conclusions predicted from molecular phylogenetical and biochemical data: (1) The ultimate base number of Eupatorieae is 17, and the lower numbers are derived by successive dysploid reductions; (2) A reduction in chromosomal and total karyotypic length accompanied by evolutionary advancement has been revealed for some genera and species within this tribe; (3) A high base number of x = 17 in Eupatorieae is considered to be derived directly from one of the members of Heliantheae with n = 17 to 19.

Five new furanoeremophilanes were isolated from three Gynoxys species. The structures of three 3α,6β-diacyloxyfuranoeremophilanes previously isolated from G. sancto-antonii have to be revised to the corresponding 1β,6β derivatives.

The aerial parts of D. floribundum afforded, in addition to known compounds, 10 new clerodane derivatives while D. ericoides gave 2-beta-hydroxyhardwickiic acid and widespread compounds. The structures were elucidated by high field NMR spectroscopy. The chemotaxonomic aspects are discussed briefly.

The aerial parts of Olearia teretifolia afforded, in addition to two known diterpenes, 39 new ones, 20 ent-clerodanes and 19 ent-labdanes. Furthermore, a new enediynediene and coniferyl acetate were present. The structures were elucidated by high field NMR techniques. Chemotaxonomic aspects are discussed briefly.

From 12 Ursinia species, in addition to known compounds, 31 new sesquiterpene lactones, 10 being germacranolides, 19 guaianolides, one eudesmanolide and a rearranged one, were isolated. Furthermore, seven sesquiterpene acids and methyl esters, including two fulvenes and a rearranged eudesmane, a nerolidol and seven farnesol derivatives, a furosesquiterpene derived from dehydrolasiospermane, three eudesmane and three eremophilane derivatives as well as a triynene were present. The structures were elucidated by high field NMR techniques. The chemistry supports the placement of the genus in the tribe Anthemideae, probably as a subtribe, together with related South African genera.

Tamaulipa azurea gave two new seco-labdanes. Bishopiella elegans gave a known nerolidol derivative and a guaianolide. Campuluclinium megacephalum gave a tremetone derivative while Asanthus solidaginifolius afforded, in addition to polyalthic acid, two known germacranolides and large amounts of a cyclopropanogermacranolide, so far only isolated in trace amounts from a Cronquistia species. Cronquistianthus trianae also afforded germacranolides.

The aerial parts of Chrysocephalum ambiguum afforded, in addition to two known diterpenes, 28 new ones, 22 ent-labdanes, four ent-manoyloxide derivatives and two monocyclic diterpenes derived from helipterol. The structures were elucidated by high field H-1 NMR spectroscopy.

Investigation of 11Aspilia species afforded several known kaurane derivatives and other diterpenes. FromA. eenii a highly oxygenated germacrane bisepoxide was isolated. Comparison of the1H NMR data with those of several germacrane derivatives fromSenecio andLigularia species, spin decoupling and NOED led to corrections of the structures of several compounds.

The aerial parts of Brickellia californica afforded in addition to widespread compounds seven guaianolides, three of them not reported previously, and a germacranolide. From B. lemmonii 11 new ent-labdanes and three known ones were isolated. Structures were elucidated by high field NMR techniques.

From the aerial parts of Siegesbeckia orientalis, in addition to a known sesquiterpene lactone, nine new germacranolides, three melampolides, three geranylnerol derivatives and three ent-pimarenes were isolated. From Guizotia scabra a new eudesmanolide was obtained. The structures were elucidated by high field NMR techniques. The chemotaxonomic aspects are discussed briefly.

A reinvestigation of Aristeguetia buddleaefolia gave 16 new labdanes and two nor-labdanes, while A. glutinosa afforded, in addition to large amounts of 8,15-dihydroxylabdane, three new nor-labdanes. Badillao salicina gave six new cis-clerodanes and Grosvenoria rimbachii, guaianolides and tremetone derivatives, four of which were new. The structures were elucidated by high field NMR techniques and a few chemical transformations. The chemotaxonomy is discussed briefly.

The aerial parts of Calocephalus knappii afforded several known kaurene and beyerene derivatives as well as one new ent-kaur-16-ene with a malonyloxy group. Myriocephalus guerinae gave two known labdanes, one being present also in Pogonolepis muelleriana.

From the aerial parts of two Haeckeria species, in addition to known compounds, 19 new eremophilan-12-oic acids, one being a seco-nor derivative, two eudesman-12-oic acids and three germacran-12-oic acids were isolated. The other species only gave known compounds which in part are of taxonomic relevance. The structures were elucidated by high field NMR spectroscopy. The chemotaxonomic aspects are discussed briefly.

The aerial parts of Cronquistia pringlei afforded, in addition to some known germacranolides and guaianolides, four new guainolides a lactone with a new carbon skeleton, i.e. a heliangolide with a cyclopropane ring. The structures were elucidated by high field NMR techniques. The chemotaxonomy is discussed briefly.