The Asteraceae is characterized by structurally diverse sesquiterpene lactones and furanosesquiterpenes. In this review the tribal, subtribal and generic distribution of sesquiterpene lactones is examined and the compounds’ utility as taxonomic characters discussed. Sesquiterpene lactones fulfill the major requirements for good analytic and synthetic characters. Studies of infraspecific sesquiterpene lactone variation indicate that different elements within complex taxa are often defined by distinct chemistries, termed chemotypes. Chemotypes have been identified within many of the thoroughly investigated taxa:Ambrosia camphorata, A. chamissonis, A. confertiflora, theA. cumanensis-A. psilostachya-A. artemisiifolia complex,A. dumosa, Artemisia tridentata, Gaillardia pulchella andMelampodium leucanthum. Such an analytic usage is mostly restricted to the infraspecific level. Synthetic usage at the interspecific level and above profits from the application of a biogenetically based methodology for sorting out the complex molecules’ carbon-skeletal and substitutional features into unit characters. Cladistics or Hennigian phylogenetic systematics provides a useful framework for such an analysis. Preliminary surveys indicate that sesquiterpene lactones are especially good characters for differentiating subtribes within several major tribes: the Vernonieae, Heliantheae and Mutisieae. As yet, too few data are available for other tribes to discern such patterns. Species surveys inVernonia, Ambrosia, Iva, Parthenium,Tetragonotheca andArtemisia demonstrate that sesquiterpene lactones are useful in discerning infrageneric groups. The biogenetic cladistic analysis of the interspecific sesquiterpene lactone variation inIva shows the efficacy of this analytical methodology. At present, such biogenetically based approaches are impeded by limited biosynthetic evidence and the erratic distribution of sesquiterpene lactones within the family. Instances of apparent displacement of sesquiterpene lactones by other terpenoids (i.e. sesquiterpene furans, alcohols and acids, diterpenes, diterpene acids, etc.) at various taxonomic levels suggest that ultimately sesquiterpene lactones must be interpreted as taxonomic characters in the context of the family’s total terpene chemistry. All taxa from which sesquiterpene lactones have been reported are listed together with the compound names, major structural features and the literature cited. A less-complete listing is provided for taxa producing furanosesquiterpenes. Structures for all reported compounds are included. Two appendices listing alphabetically taxa and compounds and relevant text page numbers permit cross-indexing of plants and compounds.

Sesquiterpene lactones as taxonomic characters in the asteraceae

In the twelve years since the first review article dealing with chemical constituents of the Hepaticae appeared in this series as Volume 42 (19), several short reviews concerned with chemical constituents of bryophytes have been published (22, 96, 144, 265, 271, 647, 649, 650) In 1988, a Symposium on Chemistry and Chemical Taxonomy of Bryophytes was organised on the behalf of the Phytochemical Society of Europe; the proceedings of this meeting appeared as a book entitled Bryophytes: Their Chemistry and Chemical Taxonomy (651) The symposium concerned itself with phytochemical, biochemical, botanical, chemotaxonomical, pharmaceutical, biotechnological and environmental aspects of bryophytes as well as with the synthesis of the terpenoids and aromatic compounds bryophytes elaborate The physiological and biochemical aspects of bryophytes have also been described in a recent book Bryophytes Development: Physiology and Biochemistry (139)

Chemical Constituents of the Bryophytes

Publisher Summary The polymers are embedded in or associated with a complex mixture of relatively nonpolar lipids that are collectively called wax because of the similarity of their physical properties to those of the honeycomb material. In most plants, wax can be found on the surface and the crystalline structure of this wax is a rather unique characteristic of each species. The most widespread site of occurrence of wax is the cuticle, and the abundance of production of cuticular waxes by some aerial parts of plants allows easy removal of the most familiar and widely utilized plant waxes such as carnauba wax. Internal organs usually contain little wax, except in rare plants such as jojoba in which large amounts of wax esters are stored as the major energy reserve. This chapter presents a methodology that is useful for examining waxes and polymerized lipids. It discusses the types of compounds found in plant waxes and in lipid-derived polymers and explains their biosynthesis, degradation, and possible functions.

Cutin, suberin, and waxes

Pigments of fungi (Macromycetes).

On terpenes. CXCVIII. Isolation and structure of pinguisone from Aneura pinguis (L.) DUM.

Plant substances. XXX. Components of liverworts ( Hepaticae) Aneura pinguis (L.) DUM., Riccardia sinuata (HOOK.) TREV., R. incurvata LINDB. and Conocephalum conicum (L.) UNDERW.

V. Benešová

Papers

On terpenes. CXCVIII. Isolation and structure of pinguisone from Aneura pinguis (L.) DUM.

Plant substances. XXX. Components of liverworts ( Hepaticae) Aneura pinguis (L.) DUM., Riccardia sinuata (HOOK.) TREV., R. incurvata LINDB. and Conocephalum conicum (L.) UNDERW.

Plant substances. XXIX. Isolation and structure of two new indole alkaloids from Riccardia sinuata (HOOK.) TREV.

On terpenes. CXXIV. Structure of telekin and isotelekin, new sesquiterpenic lactones from Telekia speciosa (SCHREB) BAUMG.

On terpenes. XLI. The sesquiterpenes of ginger oil