Catherine Clabby in American Scientist:
A new discovery in a red alga is challenging some conventional wisdom about plant evolution.
As ancestors of land plants abandoned their aquatic nurseries for life on shore, they needed the means to seal in water and hold themselves up to thrive. Lignin, a strengthening and stiffening polymer common in woody plant cells, contributes to both extremely well.
Lignin production for those tasks was considered a key adaptive achievement of vascular plants, which descend from green algae. Now a University of British Columbia botanist and some highly specialized chemists have strong evidence for lignin in a red alga called Calliarthron cheilosporioides.
The finding suggests that a biological building block fundamental to the success of land plants has roots that stretch back far deeper—and maybe wider—through evolutionary time than was known.
More here.