The evolution of angiosperm lianescence without vessels–climbing mode and wood structure–function in Tasmannia cordata (Winteraceae)
Feild TS; Chalelet DS; Balun L; Shilling EE; Evans R
The lack of extant lianescent vessel-less seed plants supports a hypothesis that liana evolution requires large-diameter xylem conduits. Here we demonstrate an unusual example of a lianoid vessel-less angiosperm Tasmannia cordata (Winteraceae) from New Guinea.\n\nWood mechanical hydraulic and structural measurements were used to determine how T. cordata climbs and to test for ecophysiological shifts related to liana evolution vs 13 free-standing congeners.\n\nThe tracheid-based wood of T. cordata furnished low hydraulic capacity compared with that of vessel-bearing lianas. In comparison with most nonclimbing relatives T. cordata possessed lower photosynthetic rates and leaf and stem hydraulic capacities. However T. cordata exhibited a two- to five-fold greater wood elastic modulus than its relatives.\n\nTasmannia cordata provides an unusual example of angiosperm liana evolution uncoupled from xylem conduit gigantism as well as high plasticity and cell type diversity in vascular development. Because T. cordata lacks vessels our results suggest that a key limitation for a vessel-less liana is that strong and low hydraulically conductive wood is required to meet the mechanical demands of lianescence.