A general survey and some taxonomic implications of diterpenes in the Asteraceae

This paper provides a general survey of the occurrence of diterpenes in the Asteraceae. Data on 4351 botanical occurrences were obtained from the literature. These were grouped by skeleton for each genus. Then, the genera were grouped by subtribes, which, in turn, were gathered in tribes, followed by subfamilies. In spite of the low number of species containing diterpenes, it was possible to describe some structural features of these compounds, i.e. the skeletal types in various taxa and the positions in some skeletons that are always oxidized or never undergo oxidation in some genera. Thus, it was verified that: in the subfamily Cichorioideae, only a few of the studied species possess diterpenes, wherein kaurane is the most frequent diterpene skeleton. In the Asteroideae, the presence of diterpenes is much greater than that in the Cichorioideae and Carduoideae. At tribal taxonomic level, for example, the Astereae produce labdanes and clerodanes; Heliantheae and Eupatorieae produce kauranes and labdanes, respectively; and Calenduleae produce pimaranes. Some taxonomic implications are presented.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 291–308.     

Influence of Temperature and Photoperiod on Flowering and Tuberous Root Formation of Pachyrrhizus tuberosus

P. tuberosus, a native species of the Amazon region, was cultivatedunder different thermal regimes and photoperiods in an attemptto relate these stimuli to flower initiation and tuberous rootformation. It is shown that P. tuberosus is an intermediate-dayplant (flowers only under photoperiods above 9 h and below 16h). With regard to tuberization P. tuberosus may be considereda short-day plant: tuberization occurs only in photoperiodsbelow 16 h. High thermal regimes 30/25 C (13 h day/11 h night)delay and reduce flowering and completely inhibit tuberous rootformation. Thermal regimes of 25/20 C and 20/15 C (13 h day/11h night) were the most suitable for flowering and tuberization. Pachyrrhizus tuberosus, yam-bean, flowering, tuberization