Obcordate. Inversely heart-shaped.
Obovate. Ovate with the broader end towards the apex.
Obtuse. Blunt or rounded at the end.
Orbicular. Having a circular or nearly circular outline.
Ovary. The part of the pistil containing the ovules.
Ovoid. A solid with an oval or ovate outline.
Ovuliferous. Bearing ovules.
Panicle. General term for any loose and irregular flower-cluster, commonly of the racemose type, with pedicellate flowers.
Pedicel. The stalk of a single flower in the ultimate divisions of an inflorescence.