Increased by seeds and by layers. The seeds should be sown as soon as ripe or else stratified. They usually lie dormant the first year.
Oak. See [Quercus].
Obeliscaria. See [Rudbeckia].
Ochna. Ochnaceæ.
During summer, cuttings may be made of growing shoots.
Odontoglossum. Orchideæ.
Division. (See also under [Orchids].)
Œnocarpus. Palmæ.
Propagated by seeds or by suckers.