The order Asparagales (sensu APG 1998) is pivotal to our current understanding of monocot taxonomy and phylogeny. Recent morphological and molecular analyses have provided major new insights into its circumscription and internal phylogenetic structure, but various aspects of its evolutionary history remain elusive or poorly supported. To address further the higher-order relationships within Asparagales, we examined chloroplast sequence data from 15 families chosen to exemplify the phylogenetic diversity of the order (Agavaceae, Alliaceae, Amaryllidaceae, Anthericaceae, Aphyllanthaceae, Asparagaceae, Asphodelaceae, Boryaceae, Convallariaceae, Hyacinthaceae, Iridaceae, Laxmanniaceae, Orchidaceae, Phormiaceae and Tecophilaeaceae). Eight disjunct locations in the chloroplast genome were sequenced (spanning 17 chloroplast genes, three introns and three slowly evolving intergenic spacer regions), providing a total of 15 kb (unaligned) of DNA sequence data per taxon. Outgroup taxa included representatives from the other major monocot lineages. A parsimony-based phylogeny inferred from these data was largely congruent with previous studies, within the limits of current taxon sampling. Bootstrap analysis (performed under the Fitch parsimony criterion) provided moderate to strong support for most of the tree. The orderís monophyly was strongly upheld, as was its division into a lower Asparagales grade and a higher Asparagales clade, as indicated by Chase et al. (1995) and Rudall et al. (1997). The family Hyacinthaceae was indicated as the sister taxon of the distinctive monotypic family Aphyllanthaceae. Alliaceae and Amaryllidaceae were supported as sister taxa. Boryaceae and Orchidaceae were weakly supported as sister taxa; Boryaceae-Orchidaceae was the sister-group of the remaining Asparagales. In addition to addressing relationships within the order, we briefly discuss the identity of the sister-group of the Asparagales. We also discuss the molecular evolution of the regions examined, providing evidence of intron loss and gene deactivation in Asphodelaceae and Orchidaceae, respectively.

Key words: Asparagales, chloroplast phylogeny, intron deletion, Orchidaceae