chlorophyta: large division of chiefly freshwater eukaryotic algae that possess chlorophyll a and b, store food as starch, and cellulose cell walls; classes Chlorophyceae, Ulvophyceae, and Charophyceae; obviously ancestral to land plants
gesso: gypsum or plaster of Paris spread on a surface to make it suitable for painting or gilding (or a surface so prepared)