petiole. Stem or stalk of a leaf.
petiolule. Stem of a leaflet.
phenogam (phænogam, phanerogam). A seed-bearing plant; that is, one of the seed-bearing or flowering group of plants.
phloem. Bark or soft bast tissue.
photosynthesis. The process whereby the carbon dioxide of the air is appropriated in the formation of material for plant growth.
phyllotaxy. Mode of arrangement of leaves or flowers on the plant or stem.
pinnate. Feather-like; said of leaves in which the veins strike off from a continuing midrib, or in which the leaflets are arranged in a similar order.
pistil. The innermost member in the flower, bearing the forming seeds.
pistillate. Of pistils only; a flower that contains pistils and no stamens, or a plant that bears only pistils.
plur-annual. A plant of a tropical or semi-tropical climate that is annual in a colder country only because it is killed by frost; as tomato, castor bean.