Perianth 1. The calyx and corolla collectively, particularly if they are of the same color (see illustration monocotyledon flowers). 2. The outer envelope of a flower. 3. The cup-shaped or tubular sheath surrounding the archegonia of some liverworts.

Pericarp The mature ovary wall, the wall of the fruit or seed vessel developed from the wall of the mature ovary.

Petiole The leaf stalk

Parenchyma The soft green undifferentiated cellular tissue made up of large, bluntended cells with thin cellulose walls found in many plant organs, particularly in the pulp of leaves and fruit and the pith of stems. The tissue is involved primarily with the distribution and storage of carbohydrates.