Folium

Folium (, "leaf"), plural folia, may refer to

• a leaf of a book: see recto and verso
• Folium of Descartes, an algebraic curve
• Folium (spider), a marking on the abdomen of a spider

Brain anatomy

• Folium (brain)
• Folium vermis

Botany

• Turnsole or folium, a dyestuff
• Folium Phyllostachydis, processed leaves of bamboo
• Hydrangeae Dulcis Folium, processed leaves of hydrangea