Open Aestivation (aestivatio aperta). A form of aestivation in which the margins of the perianth-leaves do not touch one another.
Opposite (oppositus). Set against in pairs at the same level; or placed one before another.
Oval (ovalis). About twice as long as broad and rounded at the top.
Ovary (ovarium). The lower part of the pistil, which encloses the ovules.
Ovate (ovatus). Shaped like the longitudinal section of an egg, i.e., oval and narrowed towards the top.
Ovoid (ovoideus). Egg-shaped.
Ovule (ovulum). The grain-like body which contains the female reproductive cells and developes into the seed after fertilization.
Palmate (palmatus). With the divisions or branches springing from one point.
Panicle (panicula). A repeatedly branched inflorescence of more or less pyramidal or ovoid form.
Papilla (papilla). A soft superficial protuberance.