This list includes 38 Plants that start with O, from “Oakleaf hydrangea” to “Oysterleaf”. Many are ornamental or garden-friendly, and others provide food, medicine, or habitat for pollinators. Use this list to find species for borders, containers, and ecological plantings.
Plants that start with O are a varied group of trees, shrubs, perennials and succulents used worldwide. Notable examples include evening primrose (Oenothera), valued for its oil and traditional medicinal use.
Below you’ll find the table with Common name, Scientific name, USDA hardiness zones, and Type.
Common name: The everyday name used by gardeners and nurseries, so you can easily match plants to labels and catalogues.
Scientific name: The full Latin binomial helps you identify the exact species and find precise care or distribution information.
USDA hardiness zones: Shows minimum cold tolerance, letting you see whether a plant will survive winters where you live.
Type: A short habit label like tree, shrub, perennial or annual, helping you choose plants for form and use.
Plants that start with O
| Name | Scientific name | Type | USDA hardiness zones |
|---|---|---|---|
| Oregon white oak | Quercus garryana | tree | 6–10 |
| Overcup oak | Quercus lyrata | tree | 6–9 |
| Oakleaf hydrangea | Hydrangea quercifolia | shrub | 5–9 |
| Oleander | Nerium oleander | shrub | 8–10 |
| Olive | Olea europaea | tree | 8–10 |
| Onion | Allium cepa | bulb | varies |
| Oregano | Origanum vulgare | herb | 4–9 |
| Orange | Citrus sinensis | tree | 9–11 |
| Oriental poppy | Papaver orientale | perennial | 3–7 |
| Oriental plane | Platanus orientalis | tree | 6–9 |
| Oriental beech | Fagus orientalis | tree | 5–8 |
| Orange hawkweed | Pilosella aurantiaca | perennial | 3–9 |
| Orange jasmine | Murraya paniculata | shrub | 9–11 |
| Orchid tree | Bauhinia variegata | tree | 9–11 |
| Orchid cactus | Epiphyllum oxypetalum | succulent | 9–11 |
| Oca | Oxalis tuberosa | perennial | 7–10 |
| Oxeye daisy | Leucanthemum vulgare | perennial | 3–8 |
| Oxlip | Primula elatior | perennial | 3–7 |
| Ostrich fern | Matteuccia struthiopteris | fern | 3–7 |
| Osier | Salix viminalis | shrub | 4–8 |
| Osmanthus | Osmanthus fragrans | shrub | 7–10 |
| Oyster plant | Tradescantia spathacea | perennial | 9–11 |
| Oysterleaf | Mertensia maritima | perennial | 3–7 |
| Oleaster | Elaeagnus angustifolia | shrub | 3–8 |
| Oil palm | Elaeis guineensis | tree | 10–11 |
| Opium poppy | Papaver somniferum | annual | varies |
| Oilseed rape | Brassica napus | annual | 3–8 |
| Orpine | Hylotelephium telephium | succulent | 3–9 |
| Oat | Avena sativa | grass | 3–7 |
| Obedient plant | Physostegia virginiana | perennial | 3–9 |
| Oconee bell | Shortia galacifolia | perennial | 5–7 |
| Oriental arborvitae | Platycladus orientalis | tree | 5–9 |
| Oriental bittersweet | Celastrus orbiculatus | vine | 4–8 |
| Old man’s beard | Clematis vitalba | vine | 4–8 |
| Old man cactus | Cephalocereus senilis | succulent | 9–11 |
| Orange daylily | Hemerocallis fulva | perennial | 3–9 |
| Oregon grape | Mahonia aquifolium | shrub | 5–8 |
| Osage orange | Maclura pomifera | tree | 5–9 |
Descriptions
Oregon white oak
A native Pacific Northwest oak with lobed leaves and acorns; valuable for wildlife and landscapes, tolerant of dry soils once established.
Overcup oak
A swamp-adapted oak with rounded lobes and large acorns often enclosed by the cup; used for shade and wildlife habitat in wet sites.
Oakleaf hydrangea
A heat-tolerant hydrangea with large, oak-shaped leaves and white summer flower panicles that age pink; prized for fall foliage.
Oleander
An evergreen shrub commonly used in warm-climate hedges with showy, long-blooming flowers; highly drought tolerant but poisonous if ingested.
Olive
A Mediterranean evergreen grown for fruit and ornamental silvery foliage; drought-tolerant once established and valued in warm, dry gardens.
Onion
A globally cultivated bulb vegetable with layered bulbs and hollow leaves; easy to grow from seed or sets and used widely in cooking.
Oregano
A fragrant Mediterranean herb with aromatic leaves used fresh or dried in cooking; hardy, low-maintenance, and attractive to pollinators.
Orange
The familiar sweet citrus tree grown for juicy fruit and fragrant blossoms; needs frost-free conditions and regular watering for best yields.
Oriental poppy
A bold perennial with large, papery orange or red blooms in late spring and lobed foliage; excellent for sunny borders and cottage gardens.
Oriental plane
A large shade tree with peeling bark and broad leaves, valued in parks and avenues for its stature and tolerance of urban conditions.
Oriental beech
A stately European beech with smooth gray bark and dense canopy; used as a specimen or hedge and prized for autumn color.
Orange hawkweed
A low-growing herb with bright orange daisy-like flowers; vigorous and sometimes invasive, often seen in meadows and disturbed soil.
Orange jasmine
An evergreen shrub with glossy leaves and fragrant white flowers, often used as a fragrant hedge or container plant in warm climates.
Orchid tree
A tropical/subtropical tree with orchid-like, bilateral flowers and distinctive twin-lobed leaves; grown for its dramatic spring blooms.
Orchid cactus
An epiphytic cactus with flat stems and spectacular night-blooming white flowers; grown as a hanging or container plant in warm climates.
Oca
A South American tuber crop (oxalis) with tangy-flavored tubers; grown like potatoes in cool highland gardens and prized for culinary uses.
Oxeye daisy
A classic wildflower with white ray florets and yellow centers, common in meadows and roadside areas; easy to naturalize.
Oxlip
A spring-flowering primula with clusters of pale yellow, tubular flowers; prefers cool, moist, semi-shaded woodland conditions.
Ostrich fern
A large native fern with arching fronds and edible fiddleheads; popular in shady, moist gardens and naturalized sites.
Osier
A willow grown for basketry and erosion control with long, flexible shoots; fast-growing and tolerant of wet soils.
Osmanthus
Also called tea olive, this evergreen has intensely fragrant white flowers in fall and makes an excellent specimen or hedge.
Oyster plant
A tropical groundcover with rosettes of purple-backed leaves, often grown for foliage color in warm climates or as a houseplant.
Oysterleaf
A coastal herb with blue flowers and leaves tasting faintly of oysters; a niche edible prized by coastal gardeners and chefs.
Oleaster
A hardy, silvery-leaved shrub or small tree producing fragrant flowers and edible, tart fruit; tolerant of poor soils and drought.
Oil palm
A tropical palm grown commercially for edible oil; large, pinnate leaves and clustered fruit bunches require warm, humid conditions.
Opium poppy
An annual with showy papery flowers and rounded seed capsules, grown ornamentally and historically for opiate production (regulated in many regions).
Oilseed rape
A cool-season brassica grown for oil-rich seeds (canola) and as a cover crop; yellow spring flowers also attract pollinators.
Orpine
A fleshy-leaved sedum with clusters of late-summer pink to purple flowers, valued in rock gardens and for drought-tolerant borders.
Oat
A cool-season cereal grain with tall stems and oat panicles; grown for food, fodder, and as a cover crop in temperate regions.
Obedient plant
A sturdy, uprightsided perennial with tubular flowers that stay in position when moved, making it excellent for borders and pollinators.
Oconee bell
A rare Appalachian wildflower with nodding, bell-shaped white flowers; prized by collectors and native-plant gardeners for woodland settings.
Oriental arborvitae
A conifer commonly called oriental arborvitae with dense, aromatic foliage; used for screens, hedges, and windbreaks in temperate gardens.
Oriental bittersweet
A vigorous climbing vine with orange fruit capsules that split to reveal red seeds; ornamental but invasive in many regions.
Old man’s beard
A fast-growing clematis with creamy clusters of small flowers and feathery seedheads; can cover fences and scrubby trees when uncontrolled.
Old man cactus
A columnar cactus notable for its long, white hair-like spines giving an “old man” appearance; grown as a striking container specimen.
Orange daylily
A tough, naturalizing daylily with bright orange blooms; easy to grow in many soils and often used for mass plantings.
Oregon grape
An evergreen shrub with holly-like leaves, yellow spring flowers, and blue edible berries; widely used in shady landscapes and for erosion control.
Osage orange
A thorny small tree producing large, bumpy green fruits; historically used as hedgerow and windbreak, also called hedge apple.