Opaque. Dull; neither shining nor translucent.
Opposite. Said of leaves, branches, buds, etc., on opposite sides of a stem at a node.
Orbicular. Circular. Page [xii.]
Oval. Broadly elliptical. Page [xii.]
Ovary. The part of a pistil that contains the ovules. Page [xiii.]
Ovate. Egg-shaped, with the broad end basal. Page [xii.]
Ovoid. Solid ovate or solid oval.
Ovule. The part of a flower which after fertilization becomes the seed.
Palmate. Radiately lobed or divided; hand-shaped.
Panicle. A loose, irregularly compound inflorescence with pedicellate flowers. Page [xiv.]