13 Plants That Start With O

When we think of “O” plant species, some things that spring to mind probably include onions, oak trees, and olives. But there are much more to choose from! In this article, we’ve picked out a bunch of plant species that start with the letter O – let’s dive in!


In mid-to-late springtime, this attractive, curved, evergreen plant has silky, finely serrated, dark green leaves that are wonderfully complemented by intensely perfumed, jasmine-like white flowers. It will brighten up a shaded section of the yard while in bloom, and as an evergreen, it would provide a great foil for those other plant species and greenery.

Little pruning is needed when caring for these plants. Simply remove any misaligned, broken, or unhealthy stems in springtime and spread a liberal layer of 5-7cm (2-3in) well-rotted gardening compost or manure fertilizer around the bottom of the plant.


Oleander is a shrub or tree that is grown as an attractive and aesthetic plant in moderate and subtropical climates around the world. Because it is so widely farmed, no specific area of origin has been determined, however, it is commonly connected with the Mediterranean Area.

It is most often cultivated as a shrub, although it can be encouraged to grow into a tiny tree with a solitary trunk. It is dry and flood-tolerant, but not temperature tolerant. The five-lobed flowers are white, pinkish, or crimson and grow in bunches all year, culminating in the summertime.

The fruit is a long, slender pair of receptacles that split apart to release many downy seeds when mature.


Orchid trees do not produce orchids, but they do produce flowers that mimic the blooms of some orchids. Hummingbirds are drawn to the gorgeous blooms. The Bauhinia genus has hundreds of tree, bush, and vines species that occur primarily in subtropical areas around the globe.

Some are evergreen, while others lose their foliage during the wintertime or during periods of dryness. The broad, velvety leaves of an orchid bush are 2 to 6 inches (5 to 15 centimeters) thick and heavily lobed.

However, based on the species, this tree is primarily admired for its spectacular blossoms, which can be purple, pink, crimson, orange, golden, or white. Orchid trees have the capacity to produce many trunks and for limbs to grow and then fall. The majority of trees bloom from late winter to early June.

Ornamental Pomegranate

is an uncommon decorative pomegranate variety with salmon-pink double blossoms and a lighter-colored petal margin. On just about any rich soil, any rooted plant will bloom freely.

It favors a warm location, like against a south-facing building, but will bloom in a well-sheltered sunny location, this is because it doesn’t need as much heat as edible plants. 

It is believed to have developed in the region of Iran east to North India, although it has been grown for so long (many millennia) that its real native range is unknown. 


The Oncidium family is very big and has many different flower kinds. The most frequent floral variation is known as the “dancing lady.” They have short foliage, pseudobulbs, and spreading bouquets with yellow and ebony blossoms.

The flowering period can happen at any point of the year, depending on species, but is often greatest in the springtime. Many varieties can bloom twice a year. It is critical to growing the plants in an environment where the evening temperatures dip below 65° in order to start up the flower peaks.

Ostrich Fern

This lovely seasonal shuttlecock fern is most lovely in April when the wide, greenish-yellow, delicate fronds unroll and filter the sunshine. It’s one of the greatest leafy plants for wet, gloomy shade, and it looks great placed in groups near bodies of water or in a forest garden among trees and shrubs.

These green leaves grow in a manner similar to the known curly fiddlehead ferns when they unroll from the root in springtime. Each leaf blade can reach a length of four feet.

In nature, the whole erect, curving, rhizomatous plant spans 5 to 8 feet in diameter and develops two to three feet tall, with the potential to grow up to 6 feet in height in damp, cool regions.

Oak Tree

A huge deciduous tree that can grow to be 20–40m tall. This variety, sometimes known as the common oak, develops and flourishes to create a wide and sprawling crown with robust branches below. Oak leaves have 3-6 uneven ‘thumb’ like prongs on either surface of the leaf, giving it a zigzag bordered appearance.

Insects produce tiny discs on the bottom of the tree, which are known as galls, but they do not harm the plant. Leaves will begin to fall in the months of October and November. After a certain point, the oak begins to experience ‘crown death,’ which is a fundamental aspect of its life cycle.

As the name implies, the topmost branches will be the first to perish. The wood of the trunk of the tree will also decay and degrade without harming the tree, so oaks frequently look to be three-quarters dead while remaining healthy.

Oconee Bells

The Oconee Bells are a unique and lovely plant that can only be found in a few areas in the southeastern Appalachian Mountains. The evergreen shrub thrives in the shaded area of wet, well-drained hillsides, ditches, and rocky areas. In the springtime, light pink or ivory bell-shaped blooms blossom.

The plant’s shiny spherical leaves remain on the plant all year, changing from green to a rich dark red in the wintertime. Northern Oconee Bells are classified as vulnerable in North Carolina, while Southern Oconee Bells are classified as endangered, and neither can be harvested in the wild.


Oregano is a common household herb. For millennia, humans have used it to flavor foods and treat medical issues. It is included in the Mediterranean diet. The herb has small leaves that impart a strong aroma and flavor to a range of savory meals.

When in bloom, the shrub produces pink or purple blossoms that are delicious. It is gluten-free and acceptable for vegetarian and paleo diets as an ingredient.


Oxalis is a huge and diversified plant family that offers some beautiful ornamental species. Sadly, gardeners typically associate it with weeds because certain kinds are quite invasive.

Many oxalis are non-invasive decorative species with beautiful flowers that make wonderful perennials for rockeries, garden beds, and containers, such as indigenous wood sorrel, Oxalis acetosella, which have delicate white flowers in springtime and looks lovely naturalized in a forest garden beneath trees. ~

Although oxalis is harmful to pets, the bitter taste should dissuade most animals from consuming it.


The onion, commonly known as the bulb onion or common onion, is the most frequently grown species of the Allium family. The onion crop has a spread of thin, bluish-green foliage, and when a specific day length is achieved, the bulb at the plant’s root starts to grow.

The bulbs are made up of shorter, compacted subterranean stalks that encircle a single bud at the stem’s end. The plant is vulnerable to a variety of pests and illnesses, including the onion bug, the onion eelworm, and numerous fungi that cause withering.

Onions are grown and utilized all over the globe. They are typically served fried, as a veggie, or as a component of a cooked culinary dish, although they can also be consumed fresh or used to make jams or condiments. When sliced, they have a strong odor and might irritate your eyes.

Orange Jessamine

Orange jasmine, which fills the air with the delicious scent of orange blooms, is a wonderful addition to any tropical landscape. If you want to attract pollinators, birds, or insects to your yard, orange jasmine is a terrific option. Murraya orange jasmine care is also relatively straightforward.

This attractive plant is a small annual plant with round, lustrous, vibrant green foliage up to 2 3/4 inches in length that grows from intriguing, twisted stems.

Throughout the spring, bunches of tiny, aromatic flowers emerge, followed by vivid bright red fruits in the summer. The flowers are highly fragrant and look like orange blossoms, and they bloom all year.

Olive Tree

Olive trees are a type of evergreen shrub in the Oleaceae group that are great for producing a Mediterranean-style landscape. The olive tree is indigenous to the Mediterranean region of Europe, Asia, and Africa. These plants come in a number of different forms.

Many of these trees have a wide age range as well. Fruiting olive trees are prohibited in several places of the southwestern United States due to excessive fruit falling. This causes a hazard by blocking drains and coloring driveways and patios.

Unwanted fauna is also drawn to the fruits. The olive tree’s root network is so strong that it can regenerate itself even if the tree’s above-ground body is damaged by freezing, wildfire, or disease. The flowers of the olive tree can also produce large amounts of pollen, which can become a problem if people are suffering from allergies. 

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