Flowers That Start With O

Here are the varying types of flowers with names that begin with the letter O. With an emphasis on common and easy-to-grow varieties.

Obedient Plant

Physostegia virginiana (otherwise known as the Obedient Plant) is a perennial herb in the family Lamiaceae.

It gained its name because you can bend the individual flowers in any direction.

The physostegia genus consists of flowering ornamentals, native to North America.

In general, physostegias are often used as filler or accent flowers due to their large number of small star-shaped blooms.

Obedient plant (Physostegia virginiana)

Obovate Peony

Obobate Peony (Paeonia obovata), or round-leaf peony, is a species of Paeonia that was first discovered in the mountains of Japan.

These single blooms come in many colors ranging from bright red to pink to white and where the Paeonia obovata variety has the most bright red color.

They typically grow to about 0.9m tall

This plant has white to purple-red flowers and its lower leaves consist of no more than nine leaflets or segments. 

Obovate peony (Paeonia obovata)

Ohio Spiderwort

Ohio Spiderwort (Tradescantia ohiensis) is a herbaceous perennial plant.

It is a species of Tradescantia native to the Midwestern United States.

This perennial wildflower blooms between March-May. The flower has three petals, curving at the end.

The flower is blue and has yellow stamens that create a showy center of pollinator interest.

Tradescantia ohiensis also produces large, heart-shaped leaves on long stems coming from an underground rhizomatous root system.

The variety pictured below is known as the blue jacket.

Ohio spiderwort (Tradescantia ohiensis)

Old Lady Cactus

Old Lady Cactus, scientifically known as “Mammillaria hahniana”, is a common name for several species of cacti.

Old lady cacti typically grow to 25 cm in height by 50 cm in width and have large densities of spines.

Old lady cacti can live for up to 200 years.

In the spring or summer, this cactus sprouts red or purple flowers around the top.

Old Lady Cactus (Mammillaria Hahniana)

Old Man of the Andes

Old Man of the Andes (Oreocereus Celsianus)

Oleander Plant

Oleander plants (Nerium Oleander) can be found as a common ornamental plant used in landscaping, as well as the ever-popular Oleander flower.

Oleanders are native to Asia and Africa; however, they can grow almost anywhere given proper conditions.

They are an upright, rounded evergreen sub-tropical to tropical shrub that blossoms purple, pink, or white five-petaled funnel-shaped flowers during the summer to fall months.

Oleanders typically grow fast and as they bloom all year round, they are great flowers for home gardens.

Oleander Plant (Nerium Oleander)


Orchids are the largest family of flowering plants and within that, there is huge variety.

Orchids come in all types: terrestrial, epiphytic (hanging), lithophytic (growing among stones), and many hybrids!

Equally, you can find Orchids in many different colors such as: white, yellow, pink, and red.

Orchids can be found all across the world including Australia, New Zealand, North America, South America, and even Antarctica! (except on glaciers)

They are some of the most popular flowers to grow in gardens.

Orchid. (Orchidaceae).

Oregon Grape

The Oregon grape is a handsome, evergreen shrub that is native to Oregon and northwestern California.

The Oregon grape plant has two kinds of leaves — large elliptical basal leaves that are green on the upper surface and silvery underneath, and smaller yellow-green to blue-green needle-like leaves surrounding the flower clusters.

The flowers are small, yellow, and inconspicuous, but Oregon grape plants are prized for their large clusters of purple-blue berries that attract wildlife.

Oregon grape is an important food source for birds, bears, and small mammals including raccoons, foxes, and deer.

Oregon Grape (Mahonia)

Oriental Lily

The Oriental Lily is a vibrant, bushy flower that can be grown both in pots and directly in the soil.

Oriental Lilies are one of the most versatile types of flowers because they come in various colors and shades.

They go well with each other when planted side by side, creating breathtaking combinations for outdoor areas.

Oriental lilies are admired for their pleasantly smelling perfume and tend to bloom during the mid-to-late summer.

Stargazers are easy to grow and do best in full sunlight. 

Oriental Lily. (Stargazer).

Oriental Poppy

Oriental Poppy. (Papaver).

Ornamental Onion

Ornamental Onion. (Allium).


Osteospermum. (Calendula Family, Cape Daisy).

Oyster Plant

Oyster plant (Acanthus mollis) is a herbaceous plant of the family Acanthaceae which is commonly known as bear’s breeches.

This species of plant has thistle-like leaves with large spiny marginal teeth and white flowers.

Oyster Plant. (Acanthus mollis).

Ox Eye Daisy

Ox Eye Daisy. (Leucanthemum vulgare).

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