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1986. On the presence of elastoviscin in all subfamilies of the Orchidaceae and the homology to pollenkitt. -Nord. J. Bot. 6: 321-324. Copenhagen ISSN 0107455X.Elastoviscin is newly described for the most primitive subfamily of the Orchidaceae, the Apostasioideae. The characteristics of pollenkitt and elastoviscin are compared. Both substances are highly related. The present data are used to develope some thoughts on a possible evolution of elastoviscin in the Orchidaceae. We draw the conclusion that elastoviscin could be regarded as pollenkitt until more data are available. R. Schill and M . Wolter, Inst. fur Systematische Botanik und Pflanzengeographie der Ruprecht-Karls-Utiiversitat Heidelberg, Im NeuenheimerFeld 328, 0-6900 Heidelberg, B. R. D .

R. 1988. The ontogeny of pollinia and elastoviscin in the anther of Doritis pulscherrima (Orchidaceae). -Nord. J. Bot. 8: 77-88. Copenhagen. ISSN 0107-055X.The ontogeny of pollinia of Doritis pulcherrima shows some features not commonly found in other angiosperms. The cell wails of the mature pollinium are almost identical with those of the pollen mother cells, and a callose envelope is lacking during the formation of sporopollenin. This fact may be related to the absence of a clear substructure of the exine and its low resistance to acetolysis. An exine is found only at the outer tetrads of the pollinium. The pollen grains in the tetrads possess irregularly spaced cell walls. The ontogeny of elastoviscin (specialized pollenkitt) begins in the ground cytoplasm of some tapetal cells, where small droplets are surrounded by myelin-like structures. Before anthesis the droplets fuse, flow into the loculus, and attach the pollinia to the stipe, thus forming a pollinarium. In the region in front of the elastoviscin-producing cells, some cells with specialized helical wall thickenings develop. C. Seuffert and R. Schill, Insr. furSyst. Boranik und Pflanzengeographie der Univ. Heidelberg, Im Neuenheimer Feld 328, 0-6900 Heidelberg, FRG. -M . Wolter, Boranisches Inst. und Botanischer Garren der Univ. Bonn, Meckenheimer Alee 170, 0-5300 Bonn, FRG. Q NORDIC JOURNAL OF BOTANY NORD J. BOT. 8: 77-88. STRUCT 073 Nord J . Bot. 8 ( I ) (1988) Nord J . Bot. X ( 1 ) ( I Y X X )

Using a highly diastereoselective intramolecular acrylate [4+2] cycloaddition as the key step, a short route from 3‐furaldehyde to a bicyclic building block for the synthesis of neoclerodane diterpenes was developed. A first attempt featuring a conjugate methylation of a dienyl lactone failed, but a streamlined sequence using an all‐encompassing intramolecular Diels–Alder reaction of a sterically congested 1,3‐diene was successful.

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