From delicate orchids to mighty oak trees, there is a huge range of amazing plants starting with O.
Here are 25 of my favorite flowers, trees, grasses, bushes, and fruits. Make sure you also check out our list of 25 appealing flowers that start with O.
Plants that Start with O – Quick Look
- Orchid
- Oconee Bells
- Okra
- Onion
- Ostrich Fern
- Orange Tree
- Ophiopogon
- Orchid Vine
- Oxalis
- Oregano
- Opuntia
- Oncidium
- Olive Tree
- Obedient Plant
- Old Man of the Andes
- Oak Tree
- Osage Orange
- Osmunda
- Oxblood Lily
- Orthosiphon
- Orange Jessamine
- Ornithogalum
- Old Lady Cactus
- Orange Daylily
- Osteospermum
1. Orchid
- Common Name(s): Orchid
- Scientific Name: Orchidaceae
- Native to: Cosmopolitan
There are many varieties of orchids and they are frequently used as crests and symbols. Costa Rica, Colombia, and Honduras all have a species of orchid as a national flower.
As well as being decorative, they are frequently used in perfume and they are also consumed. In Turkey, the tubers are ground and made into a beverage called salep.
2. Oconee Bells
- Common Name(s): Oconee bells, Acony bell
- Scientific Name: Shortia galacifolia
- Native to: North America
These rare plants can be found in the Appalachian Mountains. Its discovery became quite a tale, as botanists as a search for the flower in the wild stretched to over 50 years.
3. Okra
- Common Name(s): Okra
- Scientific Name: Okra, Ladies' fingers
- Native to: West African, Ethiopian, Southeast Asian, and South Asian (disputed)
The pods can be cooked and feature heavily in many cultures’ cuisine. It can be quite slimy, but any acidic food can balance them out. They are great cooked, raw, or pickled.
4. Onion
- Common Name(s): Onion, Bulb onion, common onion
- Scientific Name: Allium cepa L.
- Native to: Southwestern Asia
This well-known vegetable is great at adding flavor to dishes, and making you tear up. This is due to compounds that are released into the air when the onion is cut and irritate the nerves around the eyes.
5. Ostrich Fern
- Common Name(s): Ostrich fern, Fiddlehead fern, Shuttlecock fern
- Scientific Name: Matteuccia
- Native to: Temperate regions in the Northern Hemisphere
This plant is often used decoratively and expands to fill a large space when fully grown. The sprouts are considered a delicacy in Japan.
6. Orange Tree
- Common Name(s): Orange Tree
- Scientific Name: Citrus × Sinensis
- Native to: Southern China, Northeast India, and Myanmar
The earliest mention of oranges can be found in Chinese literature dating back to 314 BCE. They are now the most common cultivated fruit tree in the world.
The oranges we know today are actually a hybrid, a cross between pomelos and mandarins.
7. Ophiopogon
- Common Name(s): Ophiopogon, Lilyturf
- Scientific Name: Ophiopogon
- Native to: Tropical East, Southeast, and South Asia
Although this plant has a grass-like appearance, it isn’t related to true grasses.
It is used as a herb in traditional Chinese medicine to treat dry mouths, coughs, and constipation.
8. Orchid Vine
- Common Name(s): Orchid vine, Wooly congea, Shower orchid, Shower of orchid
- Scientific Name: Congea tomentosa
- Native to: Myanmar and Thailand
This tropical evergreen has become popular in many regions worldwide as a decorative trailing vine. It’s easy to grow in any soil type, providing it has heat and good sunlight.
9. Oxalis
- Common Name(s): Oxalis
- Scientific Name: Oxalis
- Native to: Worldwide
These plants have been eaten around the world for millennia. Uses include alleviating thirst, making desserts, alleviating sore throats, treating nausea, and as an aphrodisiac.
10. Oregano
- Common Name(s): Oregano, Marjoram
- Scientific Name: Origanum vulgare
- Native to: Temperate regions in the Northern Hemisphere
Oregano is well known as a culinary herb and is especially present in Greek, Italian, Mexican, French, and Turkish cuisine.
Perfect for the herb garden, they are also grown ornamentally and can vary in leaf type and flower color.
11. Opuntia
- Common Name(s): Prickly pear, Pear cactus
- Scientific Name: Opuntia
- Native to: The Americas
The cacti produce a fruit that is eaten throughout Mexico and the Mediterranean. It can be used to make a refreshing agua fresca, and is also a prime food source for the giant tortoises of the Galapagos Islands.
12. Oncidium
- Common Name(s): Oncidium, Dancing-lady orchid, Golden shower orchid
- Scientific Name: Oncidium
- Native to: The Americas
These beautiful orchids grow bright ruffled flowers in shades of yellow, red, white, and pink. They are popular with florists and can be easily hybridized.
13. Olive Tree
- Common Name(s): Olive Tree
- Scientific Name: Olea europaea
- Native to: The Mediterranean Basin
A core part of the Mediterranean diet, the olive is now popular worldwide. About 90% of all harvest is turned into oil.
14. Obedient Plant
- Common Name(s): Obedient plant, Obedience, False dragonhead
- Scientific Name: Physostegia virginiana
- Native to: North America
The name of this plant refers to its odd characteristic of staying in place when pushed to one side. It’s a great garden flower if you want late-season flowers to bloom.
15. Old Man of the Andes
- Common Name(s): Old man of the Andes, Old man of the mountain
- Scientific Name: Oreocereus celsianus
- Native to: The Andes
The unusual name of this plant comes from its natural habitat and the fluffy white hair that it grows. In spring, it grows long, tubular red flowers.
16. Oak Tree
- Common Name(s): Oak Tree
- Scientific Name: Quercus robur
- Native to: The Northern Hemisphere
A popular tree due to its resistance to insect and fungal attacks, the wood is great for lumber and commonly used in building and furniture.
17. Osage Orange
- Common Name(s): Osage orange, Horse apple, Hedge apple tree,
- Scientific Name: Maclura pomifera
- Native to: Europe
This tree is a member of the mulberry flower. Despite its tasty-looking fruit, the woody pulp and latex secretions make it an uncommonly consumed food.
18. Osmunda
- Common Name(s): Osmunda
- Scientific Name: Osmunda
- Native to: Temperate zones worldwide
These ferns grow easily in swamps and are used for propagating and growing orchids.
19. Oxblood Lily
- Common Name(s): Oxblood lily, Schoolhouse lily
- Scientific Name: Amaryllidaceae
- Native to: South America
Often found in Texan gardens, this bold red flower adds a striking splash of color to any flower bed. They are hardy and can survive growing in many conditions.
20. Orthosiphon
- Common Name(s): Orthosiphon
- Scientific Name: Orthosiphon
- Native to: Africa, Southern Asia, Queensland, and Colombia
This name refers to many plant species found alongside roads and in forests. The blueish flowers are reminiscent of a cat’s whiskers.
21. Orange Jessamine
- Common Name(s): Orange jasmine, Orange jessamine, China box, Mock orange
- Scientific Name: Murraya paniculata
- Native to: South Asia, Southeast Asia and Australia
22. Ornithogalum
- Common Name(s): Star-of-Bethlehem, Chincherinchee, Snake Flower, and Arab's Eyes
- Scientific Name: Ornithogalum
- Native to: South Asia, Southeast Asia, and Australia
A beautiful plant that grows small, fragrant flower clusters attracting bees and fruits that bring birds to the garden.
23. Old Lady Cactus
- Common Name(s): Old lady cactus
- Scientific Name: Mammillaria hahniana
- Native to: Central Mexico
These cacti produce reddish-purple flowers among a thicket of white down. The flowers grow to form a circle and make a bright crown for the plant.
24. Orange Daylily
- Common Name(s): Orange day-lily, Tawny daylily, Corn lily, Tiger daylily, Fulvous daylily, Ditch lily, Fourth of July lily
- Scientific Name: Hemerocallis fulva
- Native to: Asia
These bright and showy flowers are usually grown ornamentally, but they can also be eaten. Their leaves and shoots can be eaten both raw and cooked. The dried flowers are a great ingredient to thicken soup.
25. Osteospermum
- Common Name(s): Daisybushes, African Daisy
- Scientific Name: Osteospermum
- Native to: Africa
These look like common daisies except with vibrant pink petals rather than white. They love a warm and sunny position in parks and meadows.