More than 400,000 plant species have been described. Mosses, liverworts and hornworts (bryophytes) have ca. 20,000 living species. This is little more than the 13,000 species of lycophytes and monilophytes combined. "Green algae" also comprise ca. 13,000 species while there are only ca. 1,000 species of gymnosperms (such as pines and cycads). However, gymnosperms were much more diverse and dominant during the Mesozoic Era when dinosaurs were alive. Today it is the flowering plants (angiosperms) that are dominant with at least 352,000 living species. Botanists preserve plant specimens by spreading and drying them on newsprint (often using a plant press). Once dry, the specimens are mounted on white paper and labeled with locality data. You can use the gallery web to compare the morphology of herbarium specimens with photos of the living plant.