ABSTRACT
Historically, a prevalent North American taxonomic tradition was to recognize the lilioid monocotyledons as a subclass (Liliidae) comprising two orders: Liliales and Orchidales (Cronquist, 1981; FNA, 2003). As defined, the group excluded Cyclanthales and Pandanales, which were assigned to a different subclass (Arecidae). Subsequent molecular studies (e.g., Figure 2.1) have rendered that concept of Liliidae indefensible phylogenetically, with the former Liliid taxa resolving not within a single clade but as various disparate groups that currently are distinguished taxonomically as orders. Yet, the higher-level phylogenetic interrelationships based on molecular data are by no means compelling even when accompanied by high levels of internal support, given the all-too-familiar pattern of long external branches and short internal branches that characterize the placement of some of the more contentious groups such as Dasypogonales and Dioscoreales. Hypothesized interrelationships among major monocotyledon groups based on phylogenetic analyses of complete cpDNA genome sequence data (modified from <xref ref-type="bibr" rid="CIT00251">Barrett et al., 2016</xref>; <xref ref-type="bibr" rid="CIT01421">Givnish et al., 2018</xref>). These results provide no support to maintain the former subclass Liliidae, which is polyphyletic by these analyses. Taxa containing OBL North American indicators are highlighted in bold. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315166339/14f122ee-bca8-4b87-a405-460c8bd58982/content/fig2_1_B.tif"/>
