[Distribution of hydrocyanic Acid in cormophyta: 15.1 new observations on cyanogenesis in Rosaceae].

Prunasin was isolated from leaves and roots of Aruncus silvester (= A. dioicus), leaves of Gillenia trifoliata and seedlings of Kageneckia lanceolata (all Spiraeoideae). Chamaebatiaria millefolium (Spiraeoideae - Sorbarieae) was found to be cyanogenic; in this instance the cyanogenic constituent seems to be different from prunasin, however. Prunasin was isolated also from buds and very young shoots of Crataegus irrasa (Maloideac - Crataegeae). Very young leaves of Crataegus cuneata and C. pedicellata also contain prunasin-like glycosides. Adenostoma fasciculatum, A. sparsifolium, all taxa of Cercocarpus tested and Coleogyne ramosissima were shown to have more or less strongly cyanogenic leaves. Together with Kerria, Neviusia and Rhodotypos these genera deviate from true Rosoideae by being cyanogenic and by having the basic chromosome number 9 instead of 7. The cyanogenic compounds of these taxa seem not to be derived from phenylalanine. Prinsepia uniflora (Prunoideae) has cyanogenic young shoots which do not contain prunasin or a similar compound. Within the species Aruncus silvester, Sorbus aria and Sorbus aucuparia cyanogenesis of leaves was found to be a highly variable character. The taxonomic meaning of cyanophoric compounds in Rosaceae is discussed briefly.