| Scientific Name | Common Name(s) | Life History | Growth Form | |
|---|---|---|---|---|
|
Oenothera sinuosa | Wavyleaf beeblossom, wavy-leaf gaura | Perennial | forb |
|
Oncosiphon piluliferum | globe chamomile, stinknet | Annual | forb |
|
Onobrychis viciifolia | esparcet, sainfoin, holy-clover | Perennial | forb |
|
Onopordum illyricum | Illyrian thistle, Illyrian cottonthistle | Biennial | forb |
|
Onopordum tauricum | Taurian thistle, bull cottonthistle | Biennial | forb |
| Orobanche aegyptiaca | Egyptian broomrape | Perennial | forb | |
|
Osmanthus heterophyllus | Holly Olive, Chinese Holly, False Holly, False Olive, Holly Osmanthus | Perennial | shrub |
|
Osteospermum calendulaceum | Stinging Roger | Annual | forb |
|
Osteospermum ecklonis | blue and white daisybush , Vanstaden's river daisy, African daisy | Perennial | forb |
| Osteospermum fruticosum | trailing African daisy, freeway daisy | Perennial | forb | |
| Oxalis latifolia | Broadleaf woodsorrel, Fishtail oxalis , Garden pink-sorrel | Perennial | forb | |
|
Pancratium maritimum | Sea daffodil | Perennial | forb |
|
Papaver somniferum | Opium poppy, Oilseed poppy, Small opium poppy, Common garden poppy | Annual | forb |
| Parapholis incurva | curved sicklegrass | Annual | grass | |
|
Paraserianthes lophantha | plume acacia, Australian albizia, Cape Leeuwin wattle, plume albizia, cape wattle, crested watttle | Perennial | tree |
|
Parthenium hysterophorus | Santa Maria feverfew, quinine weed, ragweed parthenium | Annual | forb |
|
Parthenocissus quinquefolia | Virginia creeper, American ivy, five-leaved ivy, Victoria creeper, five-finger | Perennial | vine |
|
Paspalum urvillei | Vasey's grass | Perennial | grass |
|
Paspalum vaginatum | Seashore paspalum, Biscuit grass , Saltwater couch, Silt grass | Perennial | grass |
|
Passiflora caerulea | Blue passionflower, Bluecrown passionflower, blue passionfruit | Perennial | vine |
| Passiflora edulis | Passion vine | |||
|
Passiflora tarminiana | Banana passionfruit, Banana poka, Banana passion vine | Perennial | vine |
|
Passiflora tripartita | banana passionflower, banana passionfruit, banana poka | Perennial | vine |
|
Paulownia tomentosa | Empress tree, Princesstree | Perennial | tree |
| Peganum harmala | African-rue, Harmel, Syrian-rue, Wild rue | Perennial | forb |