INTERSPECIFIC VARIATION IN FLORAL FRAGRANCES WITHIN THE GENUS NARCISSUS (AMARYLLIDACEAE)

To improve our understanding of the floral biology, pollination, and s ystematics of the genus Narcissus, a comparative study was made of flo wer Volatiles from nine species native to southern Spain using headspa ce collection and GC-MS analysis. The species fell into three fragranc e types based on the identity of their major volatiles. In all but one species the fragrances consisted mainly of monoterpene isoprenoids mi xed with benzenoids: in six species trans-beta-ocimene occurred in hig h proportions, in two others it was lacking; the last species had a fr agrance dominated by fatty acid derivatives, mixed with terpenoids. Tw o of the species showed marked intraspecific variation in many of thei r volatiles. When the volatile data matrix of ail species was subjecte d to cluster analyses and the resulting phenetic trees compared with c urrently recognized taxonomic groups, there was no congruence at the s ubgeneric level. However, there was considerable agreement at the sect ional level, although in most sections we studied only a single specie s. This apparent agreement was stronger when the volatiles were analyz ed according to shared biosynthetic pathways rather than treated indiv idually, pointing to the higher value of using biosynthetic pathways f or uncovering and confirming phenetic, and probable evolutionary, rela tionships among species. In terms of possible selective pressures from pollinators in shaping fragrance chemistry, available information on the pollination of our species suggested an association between fragra nce and types of pollinators. Two pollinator-fragrance groups were app arent: (1) species pollinated by insects that include butterflies and moths displayed fragrances containing volatiles typical of moth-pollin ated flowers, most particularly indole combined with high amounts of e aters, and (2) species visited exclusively by insects other than butte rflies and moths, especially by bees and flies, had fragrances lacking this combination of volatiles. Narcissus assoanus was unusual among o ur species in having both fragrance chemotypes. Future pollination stu dies of Narcissus in the field are needed to test the reliability and predictability of the proposed fragrance-pollinator associations. (C) 1997 Elsevier Science Ltd.