Perennial : a plant lasting for 3 or more years : a stem not dying back over the dry season. 

Petiole : the stalk of a leaf blade or of a compound leaf. 

Phenology : the complex annual course of flushing. quiescence. flowering. fruiting and leaf fall in a given environment. 

Pistil : the seed-producing organ. consisting usually of ovary. style and stigma. 

Palea: chaffy or transparent scale on the inflorescence. 

Palmate: like a palm with widely divergent fingers; usually of a compound leaf with leaf-lets. 

Panicle: a repeatedly branched inflorescence. 

Papillose: with soft superficial protruberances or glands. 

Paripinnate: pinnate with an equal number of members on each side of the axis and without an odd terminal one. 

Peduncle: the common stalk of more than two flowers. 

Pericarp: the outer wall of a fertised ovary or fruit. 

Petal: a single member of the corolla. 

Petaloid: like petals. 

Petiolate: leaves with stalks. 

Pinnae: the lobes of a bipinnate leaf. 

Pinnate: leaflets arranged on each side of a common axis. 

Pinnatifid: deeply lobed to about half-way down or more with the lobes pinnately arranged. 

Pinnatisect: pinnatifid down to the mid-rib. 

Plicate: plaited. 

Plumule: primary leaf-bud in an embryo. 

Pneumatophore: vertical outgrowths of roots which facilitate breathing in some swamp plants. 

Pollinia: pollen masses, as in orchids. 

Pubescent: clothed with short soft hairs. 

Pyriform: pear-shaped.