50+ Beautiful Flowers That Start With O (With Pictures & Names)

Flowers that start with O range from sweet orange blossoms to towering desert torches. Orchids, oriental poppies, oleander, and osteospermum are the names most people know. But the letter O also hides special finds, like a rare Hawaiian shrub, a bell-flowered wildflower from the Appalachians, and a bee-shaped orchid. This guide gathers 56 of them in one place.

Every plant below is real and has a verified botanical name. Each one is grown mainly for its flowers, so no entries needed an exception label. You will find border favorites, houseplants, florist picks, trees, wildflowers, and a few rarities.

A long list only helps if you can use it. So this guide sorts the plants by color, life cycle, and use. A bloom’s beauty means little if it dies in your climate. It means even less if it harms a child or a pet. Each table is explained in plain words first, so you never face a bare spreadsheet.

You will see many names that start with Orange, Oregon, and Oriental. Those words hint at color or place, and they help you spot a plant quickly. Read straight through or jump to what you need. Have a cat? Check the toxicity section first, because some lilies and daylilies are deadly to cats. Want a quick pick? Try the decision table near the end.

Quick Answer: Ten Standout O Flowers

Obedient plant is the easy late-summer star, with pink spikes that feed bees and hold their shape in a vase. Oakleaf hydrangea brings cone-shaped blooms, bold leaves, and red fall color to part shade.

Oriental poppy gives giant, papery blooms in early summer, while oriental lily gives perfume and drama, though it is deadly to cats. Orange coneflower and oxeye sunflower carry gold through the heat of summer. Osteospermum is the cheerful daisy for sunny pots, and Oswego tea draws hummingbirds with shaggy red blooms. Osmanthus and orange blossom are the scent stars of the group, and orchid tree rounds out the list as a tropical bloom with orchid-like flowers.

Read More: 60+ Beautiful Flowers That Start With I (With Pictures & Names)

Master Alphabetical List of Flowers That Start With O

This list names 56 flowers. Most entries use a common name that gardeners already know. A few are better known by their botanical name, so they appear under the name nurseries print on plant tags. Each row has a short note, so you can see at a glance what the plant looks like and where it grows best.

Flower	Botanical Name	Note
Oakleaf Hydrangea	Hydrangea quercifolia	White cone-shaped blooms and red fall leaves
Obedient Plant	Physostegia virginiana	Pink spikes whose flowers stay where you turn them
Ocean Spray	Holodiscus discolor	Creamy plumes on a western native shrub
Oconee Bells	Shortia galacifolia	Rare white bells from the southern Appalachians
Ocotillo	Fouquieria splendens	Red torch flowers on spiny desert stems
Odontoglossum	Odontoglossum crispum	Cool-growing orchid with ruffled white blooms
Odontonema (Firespike)	Odontonema strictum	Red tubular spikes, hummingbird favorite
Oenothera (Evening Primrose)	Oenothera biennis	Yellow cups that open at dusk
Ohai	Sesbania tomentosa	Rare Hawaiian shrub with orange-red flowers
Ohia Lehua	Metrosideros polymorpha	Red brush flowers, sacred in Hawaii
Ohio Spiderwort	Tradescantia ohiensis	Blue-violet three-petaled prairie native
Oklahoma Redbud	Cercis reniformis	Magenta-pink blooms on a glossy-leaved tree
Old Blush Rose	Rosa chinensis ‘Old Blush’	Soft pink, nearly everblooming old rose
Old Garden Rose	Rosa gallica	Fragrant, full-petaled heirloom rose
Old Man’s Beard	Clematis vitalba	Creamy flowers, then fluffy seed heads, invasive in places
Oleander	Nerium oleander	Pink or white clusters, highly toxic
Olearia (Daisy Bush)	Olearia × haastii	White daisy clusters on a tough coastal shrub
Olympic Bellflower	Campanula piperi	Rare violet-blue alpine bells
Oncidium (Dancing Lady Orchid)	Oncidium spp.	Sprays of small yellow-and-brown orchid blooms
Ophrys (Bee Orchid)	Ophrys apifera	Wild orchid that mimics a bee
Orange Ball Tree	Buddleja globosa	Round orange-yellow flower balls, honey-scented
Orange Blossom	Citrus × sinensis	Fragrant white blooms, wedding tradition
Orange Clock Vine	Thunbergia gregorii	Bright orange vine blooms with dark centers
Orange Coneflower	Rudbeckia fulgida	Golden-orange daisies with dark cones
Orange Cosmos	Cosmos sulphureus	Bright orange and gold heat-loving daisies
Orange Daylily	Hemerocallis fulva	Roadside orange daylily, toxic to cats
Orange Honeysuckle	Lonicera ciliosa	Orange tubular blooms, hummingbird vine
Orange Jessamine	Murraya paniculata	Jasmine-scented white blooms on a hedge shrub
Orange Milkweed	Asclepias tuberosa	Bright orange clusters, monarch host plant
Orange Sneezeweed	Hymenoxys hoopesii	Orange mountain daisies, toxic to livestock
Orange Trumpet Vine	Pyrostegia venusta	Orange flame-colored trumpets on a fast vine
Orchid Cactus	Epiphyllum hybrids	Large showy blooms in red, pink, or orange
Orchid Primrose	Primula vialii	Violet spikes with red buds for damp shade
Orchid Tree	Bauhinia purpurea	Orchid-like pink-purple blooms on a tropical tree
Oregon Fawn Lily	Erythronium oregonum	Cream nodding blooms with mottled leaves
Oregon Grape	Mahonia aquifolium	Yellow spring clusters, blue berries
Oregon Iris	Iris tenax	Lavender wild iris from the Pacific Northwest
Oregon Sunshine	Eriophyllum lanatum	Golden daisies over silvery wool
Oriental Lily	Lilium (Oriental hybrids)	Huge, perfumed late-summer lilies, deadly to cats
Oriental Poppy	Papaver orientale	Giant papery orange-red blooms in early summer
Ornamental Onion	Allium hollandicum	Purple globes on tall stems
Ornamental Oregano	Origanum laevigatum	Pink hop-like bracts with purple flowers
Ornithogalum (Arabian Star Flower)	Ornithogalum arabicum	White stars with a black center, toxic
Orpine	Sedum telephium	Pink fall flower heads on thick leaves
Osmanthus (Sweet Olive)	Osmanthus fragrans	Tiny, intensely apricot-scented blooms
Osteospermum (African Daisy)	Osteospermum ecklonis	Daisies in bright colors that close at night
Oswego Tea	Monarda didyma	Red shaggy blooms, hummingbird favorite
Our Lord’s Candle	Hesperoyucca whipplei	Towering cream flower spike on a desert yucca
Owl’s Clover	Castilleja exserta	Purple-pink carpets in California spring
Ox-Eye Daisy	Leucanthemum vulgare	Classic white meadow daisy
Oxalis (Purple Shamrock)	Oxalis triangularis	Pale pink flowers above purple clover-like leaves
Oxeye Sunflower	Heliopsis helianthoides	Long-blooming golden daisies for hot sun
Oxlip	Primula elatior	Pale yellow nodding meadow primrose
Oyama Magnolia	Magnolia sieboldii	Nodding white cups with crimson centers
Ozark Sundrops	Oenothera macrocarpa	Big yellow cups on a sprawling prairie plant
Ozark Witch Hazel	Hamamelis vernalis	Winter spidery blooms in red and orange

That table names 56 distinct flowers that start with O. Orchid tree and oleander sit far apart in character. One is a graceful tropical beauty. The other is a lovely shrub that is deadly poisonous. Both show how wide this single letter reaches.

Full Comparison Table: Sun, Water, and Bloom Time

When two plants seem equally good, sun and water needs usually pick the winner. The table below compares the main O flowers from this guide. Read the sun column first. Then check the water column and the bloom season to see if the plant fits your space and your calendar.

Flower	Sun Needs	Water Needs	Bloom Season
Obedient Plant	Full sun to part shade	Moderate	Late summer to fall
Oakleaf Hydrangea	Part shade	Moderate	Early to midsummer
Oleander	Full sun	Low	Summer
Oriental Lily	Full sun to part shade	Moderate	Late summer
Oriental Poppy	Full sun	Low	Late spring to early summer
Orange Coneflower	Full sun	Moderate	Midsummer to fall
Orange Daylily	Full sun to part shade	Low	Early to midsummer
Oswego Tea	Full sun to part shade	Moderate to high	Midsummer
Ox-Eye Daisy	Full sun	Low	Late spring to summer
Oxeye Sunflower	Full sun	Low to moderate	Summer
Osteospermum	Full sun	Low to moderate	Spring to fall
Oxalis (Purple Shamrock)	Bright indirect light	Moderate	Spring to fall (indoors)
Osmanthus	Full sun to part shade	Moderate	Fall, with a lighter spring flush
Orchid Tree	Full sun	Low to moderate	Winter to spring
Oncidium	Bright indirect light	Moderate	Often fall to winter
Ornamental Onion	Full sun	Low to moderate	Late spring
Oregon Grape	Part shade	Low to moderate	Early spring
Orange Cosmos	Full sun	Low	Summer to frost

Oleander, oriental poppy, and orange cosmos are the best picks for hot, dry, poor soil. All three bloom better when they are not overwatered. Oswego tea sits at the other end. It wants moist soil and good airflow to avoid mildew.

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Garden Favorites Among O Flowers

A handful of O flowers earn a place in almost every sunny garden. Orange coneflower and oxeye sunflower keep gold in the border for months. Obedient plant gives pink spikes in the last weeks of summer. Oswego tea fills midsummer with hummingbirds. Ornamental onion adds purple globes in late spring, just when tulips fade.

• Orange Coneflower blooms from midsummer to fall and feeds finches in winter.
• Oxeye Sunflower thrives in heat and needs almost no fussing.
• Obedient Plant spreads by roots and gives long-lasting late color.
• Oswego Tea draws hummingbirds and bees to the border.
• Ornamental Onion is ignored by deer and rabbits.

Orange coneflower and obedient plant make a strong pair. One carries gold, and the other carries pink. Together they keep a sunny border interesting through the late season.

A few care habits keep these plants happy. Divide the obedient plant every two or three years, since it spreads fast. Give Oswego tea good airflow to avoid powdery mildew. Cut oriental poppies to the ground after they bloom, because the leaves die back in summer heat. Leave orange coneflower seed heads standing for birds.

Indoor and Container Picks Among O Flowers

Only a few O plants thrive indoors, but they are worth knowing. Oncidium, called the dancing lady orchid, sends up sprays of small yellow flowers on a bright windowsill. Odontoglossum and other orchids suit cooler rooms with bright, indirect light. Purple shamrock, or oxalis, brings pale pink blooms above its purple leaves. Osteospermum thrives in sunny pots on balconies and patios.

• Oncidium likes bright light, a loose mix, and a drier rest after blooming.
• Oxalis (Purple Shamrock) closes its leaves at night and blooms most of the year.
• Osteospermum needs full sun, and its flowers close in shade or at night.
• Orchid Cactus wants bright light and a cool, dry rest in winter.

Purple shamrock is the pick for beginners. It forgives missed waterings. Just keep it away from pets, since oxalis contains crystals that can upset the stomach.

Light matters more than anything else for indoor O plants. A bright east window suits oncidium and oxalis. Avoid cold drafts and soggy saucers. Most of these plants fail from too much water, not too little.

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Florist Favorites Among O Flowers

Florists use O flowers for scent, drama, and color. Oriental lilies give big, perfumed blooms to wedding and event work. Orange blossom and osmanthus bring a sweet scent to small posies and wreaths. Osteospermum and orange cosmos add bright daisy color to casual bouquets. Obedient plant stems hold up well in a vase and add height.

• Oriental Lily is dramatic and fragrant, but it is deadly to cats.
• Orange Blossom is the traditional wedding flower and smells sweet.
• Obedient Plant lasts about a week and adds long pink spikes.
• Oriental Poppy is stunning but short-lived, and the stems need searing.
• Ox-Eye Daisy gives a wildflower look to relaxed bouquets.

Oriental lily and obedient plant are the quiet workhorses. They hold up in the vase long after softer blooms fade. A florist’s bouquet in late summer would feel empty without them.

Good vase care doubles the life of any cut flower. Strip the leaves below the water line. Recut the stems at an angle. Change the water every two days. For oriental poppy, sear the cut stem ends in hot water for a few seconds to stop the sap from clogging them.

Rare and Unusual O Flowers

Some O plants are hard to find or hard to grow. Oconee bells is a tiny evergreen from the southern Appalachians with white bell flowers, and it is rare in the wild. Ohai is a Hawaiian shrub with orange-red flowers that is critically endangered and grows in only a few dry places. Ocotillo is a spiny desert plant that sprouts red flowers at the tips of bare stems after rain. Our Lord’s candle is a desert yucca that sends up a towering cream flower spike once in its life and then dies.

These four plants share one trait. Each wants a very specific home. That is why they stay special. If you want to grow one, buy nursery-grown plants only. Never dig wild plants, since many rare O species are protected by law.

Caution: Toxic O Flowers

Several O plants can harm pets, livestock, or people. Oleander is the most dangerous. Every part of the plant is poisonous, and even a small amount can affect the heart. Cat owners need to know about oriental lily and orange daylily. Even a small nibble or a lick of pollen can cause kidney failure in cats. Orange milkweed and Arabian star flower carry heart-affecting compounds, and orange sneezeweed poisons grazing animals.

Flower	Toxic To	Severity
Oleander	Humans, dogs, cats, horses, livestock	Severe — all parts affect the heart, can be fatal
Oriental Lily	Cats (extremely), dogs (mild)	Severe for cats — can cause kidney failure
Orange Daylily	Cats (extremely), dogs (mild)	Severe for cats — daylilies can cause kidney failure
Orange Milkweed	Dogs, cats, horses, livestock	Moderate to severe — cardiac glycosides
Orange Sneezeweed	Sheep, cattle, horses	Moderate to severe — grazing can be fatal
Ornithogalum (Arabian Star Flower)	Dogs, cats, horses	Moderate to severe — heart-affecting compounds
Ornamental Onion	Dogs, cats	Moderate — can damage red blood cells in large amounts
Oxalis	Dogs, cats, horses	Mild to moderate — oxalate crystals upset the stomach
Old Man’s Beard	Dogs, cats, horses	Mild to moderate — sap irritates mouth and skin
Oakleaf Hydrangea	Dogs, cats, horses	Mild to moderate — stomach upset

Oleander, oriental lily, and orange daylily deserve the loudest warning. Keep them away from children and pets, and never bring lilies into a home with a cat. Oxalis and oakleaf hydrangea are milder, but a chewing dog can still get sick. If a pet or child eats any plant on this list, call a vet or poison control right away.

O Flowers Grouped by Color

Orange and red bring warmth, and the letter O has plenty of both. Orange daylily, orange milkweed, orange trumpet vine, orange clock vine, orange honeysuckle, and oriental poppy all glow in the sun. Ocotillo and ohia lehua add true red to desert and tropical scenes.

Yellow and gold come next. Oxeye sunflower, orange coneflower, Oregon grape, Oregon sunshine, and Ozark sundrops fill sunny beds with gold. Oregon grape blooms early, in the first weeks of spring. Oxeye sunflower and orange coneflower carry gold through the hottest months. Evening primrose opens its yellow cups at dusk.

Pink, rose, and magenta show up in oriental lily, Oklahoma redbud, old blush rose, orchid tree, and obedient plant. Oklahoma redbud and orchid tree give the biggest show, since whole trees bloom. Old blush rose and old garden rose bring fragrance and an old-fashioned charm. Obedient plant keeps pink going into fall.

White and cream flowers include orange blossom, osmanthus, orange jessamine, oakleaf hydrangea, ocean spray, and ox-eye daisy. White glows at dusk and brightens shade. Orange blossom, osmanthus, and orange jessamine add scent to patios. Oakleaf hydrangea and ocean spray suit woodland-style gardens.

Purple, blue, and violet are the cool side of O. Ornamental onion, Oregon iris, Ohio spiderwort, and Olympic bellflower bring these shades. Ornamental onion gives bold globes. Ohio spiderwort and Oregon iris suit natural borders. Olympic bellflower is a rare alpine treasure.

Life-Cycle Groupings for O Flowers

A plant’s life cycle tells you how much work to expect. Annuals live one season, so you replant each year. Biennials flower in their second year. Perennials return on their own. Bulbs need the right winter, cold or warm, to come back. Trees and shrubs take longer to bloom but last for decades. Zones below are approximate and vary by variety, so check your own plant tag.

Flower	Life Cycle	Typical Zones
Orange Cosmos	Annual	All zones (seasonal)
Owl’s Clover	Annual	All zones (seasonal)
Osteospermum	Tender perennial, often grown as annual	10–11 (perennial), elsewhere annual
Oenothera (Evening Primrose)	Biennial	4–9
Obedient Plant	Perennial	3–9
Oswego Tea	Perennial	4–9
Orange Coneflower	Perennial	4–9
Oxeye Sunflower	Perennial	3–9
Ox-Eye Daisy	Perennial	3–8
Oriental Poppy	Perennial	3–8
Orange Daylily	Perennial	3–9
Oxlip	Perennial	4–8
Ozark Sundrops	Perennial	4–8
Oriental Lily	Perennial (bulb)	4–9
Ornamental Onion	Perennial (bulb)	4–8
Oakleaf Hydrangea	Perennial (shrub)	5–9
Oregon Grape	Perennial (shrub)	5–9
Old Garden Rose	Perennial (shrub)	4–9
Oleander	Perennial (shrub)	8–10
Osmanthus	Perennial (shrub)	7–11
Oyama Magnolia	Perennial (small tree)	5–8
Orchid Tree	Tender perennial (tree)	9–11
Oxalis (Purple Shamrock)	Tender perennial	8–11 (indoors elsewhere)

Oriental poppy and obedient plant are the two to watch. Oriental poppy disappears in midsummer, so plant it behind something leafy that fills the gap. Obedient plant spreads quickly, so give it room or divide it often.

Botanical Name Crosswalk

Common names change from place to place. Botanical names do not. Nursery tags and seed packets use Latin for this reason. It also helps you search online with confidence. Two different plants can share one common name, so the Latin name protects you from a wrong purchase.

Common Name	Botanical Name
Obedient Plant	Physostegia virginiana
Oakleaf Hydrangea	Hydrangea quercifolia
Oleander	Nerium oleander
Oriental Poppy	Papaver orientale
Oriental Lily	Lilium (Oriental hybrids)
Orange Coneflower	Rudbeckia fulgida
Orange Daylily	Hemerocallis fulva
Oswego Tea	Monarda didyma
Ox-Eye Daisy	Leucanthemum vulgare
Oxeye Sunflower	Heliopsis helianthoides
Osteospermum	Osteospermum ecklonis
Osmanthus	Osmanthus fragrans
Orchid Tree	Bauhinia purpurea
Orange Blossom	Citrus × sinensis
Oncidium	Oncidium spp.

Daisy names cause the most confusion. Ox-eye daisy and oxeye sunflower sound alike, but they are different plants. Ox-eye daisy is Leucanthemum vulgare. Oxeye sunflower is Heliopsis helianthoides. Also, oriental lily and orange daylily are both toxic to cats, even though only one is a true lily. Always check the Latin name before you bring a lily-like plant home.

What O Flowers Mean

Flower meanings vary by culture, but a good number of orange flowers carry steady symbolism. Orange blossom stands for purity, hope, and fertility, which is why brides have worn it for centuries. It is the state flower of Florida. Citrus blossoms also perfume orchards in many warm regions, including Punjab, and orange blossom water flavors sweets and drinks in the Middle East.

Orchids stand for love, luxury, and rare beauty. Osmanthus carries a meaning of love and honor in China, where its flowers perfume the Mid-Autumn Festival and flavor cakes and tea. Oriental lily stands for prosperity and passion in modern flower language. Old garden roses carry the classic meaning of love.

Some meanings are wry and old. In Victorian flower language, ox-eye daisy meant patience, and evening primrose meant inconstancy. Oleander carried a warning and meant caution. Oxalis, often sold as a lucky shamrock, is a popular gift for good luck.

Ohia lehua has a Hawaiian legend of two lovers, Ohia and Lehua, who were separated by a goddess and changed into a tree and its flower. Oswego tea is tied to American history, since settlers used its leaves as a tea substitute after the Boston Tea Party. Match the flower to your message, and remember that the same bloom can mean something different in another culture.

Decision Table: Which O Flower Fits Your Situation

You do not have to read the whole list to choose well. Start with your goal in the left column. The right column names the best O flower for it. Then check the toxicity section if you have pets or children.

If You Want…	Choose This O Flower
Gold for a sunny border	Orange Coneflower, Oxeye Sunflower, or Orange Cosmos
Late-summer pink	Obedient Plant
Hummingbird and butterfly support	Oswego Tea, Orange Milkweed, or Odontonema
Strong fragrance	Osmanthus, Orange Blossom, or Orange Jessamine
Color in part shade	Oakleaf Hydrangea or Oregon Grape
An easy houseplant with blooms	Oxalis (keep away from pets) or Oncidium
A pot or basket flower	Osteospermum
A flowering tree	Orchid Tree, Oklahoma Redbud, or Oyama Magnolia
Dry, hot, low-water gardens	Oriental Poppy, Orange Cosmos, or Oleander (keep away from pets)
A pet-friendlier garden	Oncidium, Osteospermum, or Obedient Plant (absent from this guide’s toxic list)

Orange coneflower appears first because it is easy and long-blooming. Obedient plant is a good partner for it in a family garden. Always double-check any plant with your vet if a pet is likely to chew it.

Conclusion

Flowers that start with O offer a very wide choice, from the sweet orange blossom to the rare Oconee bells. This guide sorted 56 of them by color, life cycle, and use, so you can pick with confidence. Whether you want a golden summer border, a scented patio, or an easy orchid for a sunny window, there is an O flower that fits. Use the tables above, read the toxicity notes, and start planting.

Frequently Asked Questions

How many flowers start with O?

More than 50 well-known flowers start with O. This guide lists 56, from common garden plants to rare orchids and desert natives.

What is the most popular flower that starts with O?

Orchid, oriental poppy, oleander, and osteospermum are among the most popular. Orange blossom and oriental lily are favorites for weddings.

What are the easiest flowers that start with O to grow?

Orange coneflower, oxeye sunflower, obedient plant, orange cosmos, and ox-eye daisy are very easy. Oxalis is the easiest O houseplant.

Which O flowers attract butterflies and hummingbirds?

Orange milkweed, obedient plant, and orange coneflower draw butterflies and bees. Oswego tea, odontonema, and orange honeysuckle draw hummingbirds.

Is oleander poisonous? Yes.

Oleander is one of the most poisonous garden plants. Every part can affect the heart, and even dried leaves are dangerous.

Which O flower is the most dangerous?

Oleander is the most dangerous for people and pets. Oriental lily and orange daylily are the most dangerous for cats.

Are oriental lilies safe around cats?

No. Oriental lilies are among the most dangerous plants for cats. Even a small bite or a lick of pollen can cause kidney failure, so keep them out of the house.

What does orange blossom symbolize? Orange blossom stands for purity, hope, and fertility. It is a traditional bridal flower and the state flower of Florida.

Which O flowers have the strongest scent?

Osmanthus, orange blossom, orange jasmine, and oriental lily have the strongest scent. Evening primrose is scented at dusk.

Which O flowers bloom in early spring?

Oregon grape, oxlip, Oklahoma redbud, and Ozark witch hazel bloom early. Ornamental onion follows in late spring.

Which O flowers work well in dry, sunny gardens?

Oriental poppy, orange cosmos, oxeye sunflower, ox-eye daisy, and ocotillo thrive in dry sun. Oleander also loves heat but must be kept away from pets and children.

Can I grow orchids that start with O indoors?

Yes. Oncidium and odontoglossum orchids grow well in bright, indirect light. Oncidium is easier for beginners, and odontoglossum prefers cooler rooms.

What is the rarest flower that starts with O?

Ohai, Oconee bells, and Olympic bellflower are among the rarest. All three are hard to grow outside their home habitats.

Which O flowers make good cut flowers?

Oriental lily, obedient plant, osteospermum, ox-eye daisy, and orange coneflower all cut well. Keep lilies away from cats.

Where can I find a full list of flowers that start with O?

You are in the right place. The master alphabetical list above names 56 flowers that start with O, with botanical names and short notes.