THE VEGETATIVE MORPHOLOGY AND DEVELOPMENT OF THE RETICULATE-VEINED LILIIFLORAE AND THEIR PARALLEL-VEINED ALLIES

The reticulate-veined Liliiflorae consist of 22 genera of the families, Smilacaceae, Dioscoreaceae, Philesiaceae, Stemonaceae, and Trilliaceae. Their closest parallel-veined allies include 24 genera of the Liliaceae and the Alstroemeriaceae. Leaf architecture, growth habit, and leaf epidermal characters of these genera are described and compared. Primary veins fuse at the apex of most leaves studied. Secondary veins of the reticulate-veined Liliiflorae are pinnate, those of the parallel-veined allies run parallel to the leaf axis and enter the stele. Other characters of vegetative morphology are correlated with secondary vein course: pinnate secondary veins correlate with (1) climbing habit, (2) petiolate leaves, (3) free-vein endings, (4) isodiametric areoles and epidermal cells, and (5) randomly oriented stomates. Parallel secondary veins correlate with (1) caulescent nonclimbing or rosette habit, (2) sessile leaves, (3) absence of free-vein endings, (4) elongate areoles and epidermal cells, and (5) regularly oriented stomates. Studies of leaf development in one reticulate-veined species, Lapageria rosea, and one parallel-veined species, Eustrephus latifolius, indicate that there are no strong differences in distribution of growth. In leaves of both species, a basipetal growth gradient is present, but a basal intercalary meristem is absent. Mitotic activity is similarly localized in leaves of both species, throughout development, although differences in cell lineage patterns, as seen in paradermal section of intercostal panels, are apparent well before secondary vein course and stomate orientation is determined. Taxonomic conclusions from this comparative morphological survey include the following. (1) The tribe, Polygonatae, is unnatural. (2) The genus, Prosartes, should be removed from Disporum and reinstated. (3) Drymophila should be allied with Luzuriaga. (4) Ripogonum may be misplaced in the Smilacaceae. (5) The Smilacaceae and the Philesiaceae appear to be related, but Eustrephus and Geitonoplesium are very different from other members of the Philesiaceae. (6) The family, Trilliaceae is unnatural. (7) The Trilliaceae and Stemonaceae are not related