Phyllon (plural, phylla), Greek for leaf and leaves; used in many compound terms and names.

Phyllotaxis, or Phyllotaxy, the arrangement of leaves on the stem, [67].

Physiological Botany, [9].

Phytography, relates to characterizing and describing plants.

Phyton, or Phytomer, a name used to designate the pieces which by their repetition make up a plant, theoretically, viz. a joint of stem with its leaf or pair of leaves.

Pileus of a mushroom, [172].

Piliferous, bearing a slender bristle or hair (pilum), or beset with hairs.

Pilose, hairy; clothed with soft slender hairs.

Pinna, a primary division with its leaflets of a bipinnate or tripinnate leaf.

Pinnule, a secondary division of a bipinnate or tripinnate leaf, [66].