Photosynthesis Optimized across Land Plant Phylogeny.

Until recently, few data were available on photosynthesis and its underlying mechanistically limiting factors in plants, other than crops and model species. Currently, a new large pool of data from extant representatives of basal terrestrial plant groups is emerging, allowing exploration of how photosynthetic capacity (A) increases from minimum values in bryophytes to maximum in tracheophytes, which is associated to an optimization of the balance between its limiting factors. From predominant mesophyll conductance limitation (l) in bryophytes and lycophytes (fern allies) to stomatal conductance (l) and l colimitation in pteridophytes (ferns) and gymnosperms, a balanced colimitation by the three limitations is finally reached in angiosperms.

The photosynthetic capacity in 35 ferns and fern allies: mesophyll CO2 diffusion as a key trait.

Ferns and fern allies have low photosynthetic rates compared with seed plants. Their photosynthesis is thought to be limited principally by physical CO2 diffusion from the atmosphere to chloroplasts. The aim of this study was to understand the reasons for low photosynthesis in species of ferns and fern allies (Lycopodiopsida and Polypodiopsida).