pelochthi´um (πηλός, mud, ὄχθη, bank), a mud bank form; pelogenous, producing clay; pelopsammic (ψάμμος, sand), composed of mixed clay and sand; pelopsammogenous, producing clay and sand.

permobile, extremely mobile.

perquadrat, a quadrat of 16 square meters or more.

petasospore (πέτασος, sunshade), a plant with parachute-like disseminules.

petri´um (πέτρα, rock, stone), a rock formation; petrad, a rock plant; petrochthi´um (ὄχθη, bank), a rock bank formation.

petrodi´um (πετρώδης, abounding in boulders), a boulder field formation; petrodad, a plant of a boulder field.

phelli´um (φελλεύς, stony ground), a rock field formation; phellad, a rock field plant.

-philous (φίλος), loving, dwelling in.

-photic (φῶς, φωτός, light), pertaining to light; photoharmose, response to light stimuli; photometer, an instrument for measuring light.

phreti´um (φρητός, tank), a tank formation; phretad, a tank plant.