Oenothera glazioviana Large-flowered Evening Primrose, Redsepal Evening Primrose (*)
Oenothera mollissima - (*)
Oenothera stricta subsp. stricta Common Evening Primrose (*)
Olax stricta Narrow-leaf Olax
Olearia canescens Grey Daisy Bush
Olearia elliptica subsp. elliptica Peach Bush, Sticky Daisy Bush
Olearia glandulosa Swamp Daisy Bush
Olearia gravis Large Daisy Bush
Olearia microphylla Bridal Daisy Bush, Small-leaved Olearia, Starflower
Olearia nernstii -
Olearia oppositifolia -
Olearia ramosissima Blue Mountain-daisy, Much-branched Daisy Bush
Opercularia hispida Hairy Stinkweed
Oplismenus imbecillis Creeping Beardgrass, Pademelon Grass
Ornithopus pinnatus Orange Bird's-foot, Slender Serradella (*)
Orthoceras strictum Bird's-mouth Orchid, Horned Orchid
Oxalis sp. Oxalis, Wood Sorrel (*)
Oxylobium arborescens Tall Shaggy Pea
Oxypetalum coeruleum Tweedia, Southern Blue Star, Little Blue Star (*)
Ozothamnus diosmifolius Pill Bush, Pill Flower, Rice Flower, Sago Bush, Sago Flower, White Dogwood, White Everlasting
Ozothamnus obcordatus Grey Everlasting
