28 Flowers That Start With I (Names, Bloom Times & Toxicity)

Flowers that start with I are led by the iris, named for the Greek goddess of the rainbow and bred in almost every colour there is. Impatiens, Iceland poppies, Inca lilies, ice plants and ivy geraniums fill out the letter — along with one bulb regularly confused with a deadly relative.

This guide covers 28 flowers beginning with I, with botanical names, plant type, bloom season and what distinguishes each. Toxic species are flagged.

Flowers Starting With I: Complete List

Garden Mainstays

Iris

Named for the Greek goddess of the rainbow, and the genus lives up to it — irises come in nearly every colour including near-black. The flower has a distinctive structure: three upright petals called standards and three drooping ones called falls, with the fuzzy “beard” on the falls guiding bees inward. Bearded iris rhizomes must sit at the soil surface and bake in sun; planting them too deep is the single most common reason they produce leaves but no flowers. The rhizomes are toxic if eaten and the sap can irritate skin.

Impatiens

The name means impatient, and refers to the seed pods, which burst at the slightest touch and fling seed several feet — hence the other common name, touch-me-not. Impatiens is one of very few reliable annuals for genuine shade. Downy mildew changed that: sporadic greenhouse reports appeared from 2004, but in 2011 severe outbreaks hit landscape plantings across Europe and North America for the first time, devastating Impatiens walleriana. New Guinea impatiens and bred-resistant strains have largely replaced it.

Iceberg Rose

A floribunda bred by Reimer Kordes in Germany and introduced in 1958, and among the most widely planted white roses in the world. It flowers almost continuously from summer into autumn and has unusually good disease resistance, which is why it turns up so often in public planting where maintenance is minimal.

Iceland Poppy

Despite the name it comes from subpolar Asia and North America rather than Iceland. The petals are crumpled inside the bud like tissue paper and unfurl on opening. As a cut flower it is notoriously short-lived unless the stem end is seared in a flame or dipped briefly in boiling water, which stops the milky sap blocking water uptake.

Inca Lily

Alstroemeria, and one of the best cut flowers there is — two to three weeks in a vase is normal. Pull the stems from the base rather than cutting them, which stimulates more growth from the tuberous roots. The streaks and speckles on the inner petals act as nectar guides.

Iberis

Candytuft, forming low evergreen mounds smothered in white in spring, ideal spilling over a wall or edging a path. Shear it back after flowering or it goes woody and bare in the centre within a few seasons — the same rule as aubrieta and arabis. The name comes from Iberia, where many species originate.

Ivy Geranium

A trailing pelargonium with thick glossy ivy-shaped leaves, and the plant behind the cascading window boxes of Alpine villages and Mediterranean balconies. It tolerates heat and drought far better than upright zonal pelargoniums and dislikes overwatering. Like all pelargoniums it is tender and treated as an annual in cold regions.

Ixora

A tropical shrub carrying dense domed clusters of small tubular flowers in flame orange, red, pink or yellow, flowering more or less continuously in warm climates. It needs acid soil and is highly sensitive to lime — yellowing between the leaf veins is the standard symptom of the wrong pH.

Bulbs and Corms

Indian Hyacinth

Camassia, producing tall spikes of star-shaped blue flowers in late spring and naturalising beautifully in damp meadow. Its bulbs were a major traditional food for Indigenous peoples across the Pacific Northwest, slow-roasted in pits until the indigestible starches converted to sugars.

Ixia

The corn lily, a South African corm sending up very slender wiry stems topped with spikes of star-shaped flowers, often with a dark contrasting centre. The stems are so fine the flowers appear to float. It needs a hot dry summer dormancy and rots in wet summers, which is why it suits Mediterranean climates and pots elsewhere.

Ismene

The Peruvian daffodil, a Hymenocallis with extraordinary flowers in which the stamens are joined by a delicate membrane forming a central cup, with long filaments curling outward. The scent strengthens at night for hawkmoths. It is frost-tender and usually lifted and stored over winter in cold regions.

Wildflowers, Climbers and Curiosities

Ipomoea

The genus covering both morning glory, which opens at dawn and closes by afternoon, and moonflower (I. alba), which does the reverse and opens fragrant white trumpets at dusk. Both climb by twining and need something to wrap around. The seeds of several species contain toxic alkaloids and should not be eaten. Note that harmless Ipomoea alba is frequently confused with Datura, which is severely poisonous — check the botanical name.

Indian Balsam

Himalayan balsam, introduced to Britain in 1839 by Victorian plant hunters for its pink flowers and exploding seed pods. It reaches two and a half metres in a single season and is now one of the most damaging invasive plants in Europe: it out-competes native riverbank vegetation, then dies back in winter leaving banks bare and prone to erosion. The seed pods fling seed up to seven metres, and seed also floats downstream and stays viable for around two years. It should not be planted.

Indian Paintbrush

A hemiparasite — it photosynthesises but also taps the roots of neighbouring plants, usually grasses, for water and nutrients. That dependence is why it is notoriously difficult to establish in a garden and must be sown alongside a suitable host. The vivid colour is in the bracts rather than the small green flowers they surround.

Ivy

Easy to dismiss, but mature ivy flowers in autumn when almost nothing else does, providing one of the last significant nectar sources of the year for wasps, hoverflies and the ivy bee, followed by berries that feed birds through winter. It climbs by adhesive rootlets rather than twining and does not feed on the host tree, though heavy growth can shade and destabilise one.

Ironweed

Vernonia, a tall prairie perennial producing flat clusters of intensely purple flowers very late in the season, often the last thing standing in a meadow planting. The name refers to the toughness of the stems, and it is a valuable late nectar source for migrating butterflies.

Immortelle

The strawflower, whose bracts are papery and dry even on the living plant, so cut stems dry with almost no change in colour or shape. It has been used in wreaths and remembrance arrangements for centuries, which is where the name comes from.

Indigo

Indigofera tinctoria is the source of true indigo dye, extracted by fermenting the leaves — a process that shaped global trade and colonial agriculture, and eventually the colour of denim. Synthetic indigo displaced the crop almost entirely from the early twentieth century. Garden species are grown for pea-like flower spikes and fine foliage.

Ice Plant

Delosperma, a mat-forming succulent covered in daisy-like flowers of near-fluorescent intensity, with leaves carrying glistening bladder cells that give it its name. It is exceptionally drought and heat tolerant and needs sharp drainage — winter wet kills far more ice plants than winter cold does.

Isotoma

A low tender perennial producing star-shaped blue or white flowers over a long summer season, popular in containers and as a filler. Handle it with care: the sap can irritate skin and is particularly unpleasant in the eyes, so wear gloves when cutting it back.

Indian Breadroot

The prairie turnip, a legume with a starchy edible root that was a staple food across the North American plains, dried and pounded into flour or eaten fresh. It is slow-growing and was harvested at scale historically, and it is now uncommon enough that wild digging is discouraged.

Other Species in This Group

Inca Marigold

Even though they are native to Mexico, Inca marigolds are frequently referred to as African marigolds. These lovely marigolds are perennial or annual herbaceous members of the aster or daisy family (Asteraceae). In Zones 2 to 11, inca marigolds are often planted as annuals. Bright orange or yellow pom-pom-like flowers on incan marigolds grow from the summer to the late fall. Additionally, the leaves of these marigolds are pinnate and can have up to 17 lance-shaped leaflets. Inca marigolds make great companion plants as well.

Incarvillea

Beautiful exotic perennials called incarvillea are indigenous to southwest China and have stunning flowers. They are members of the trumpet vine or begonia family. Although incarvillea flowers are not related to actual ferns, they are frequently referred to as hardy gloxinia or flowery ferns. In Zones 5 to 7, these flowers that begin with the letter I thrive and are available in a variety of vibrant cultivars. Basal rosettes of fern-like leaves with airy leaflets can be found on these attractive perennials. A trumpet-shaped flower with pink petals and a yellow center is another feature of incarvillea plants.

Indian Blanket

Indian blanket flowers are among the most beautiful flowers that start with the letter “I,” in my opinion. These flowers belong to the daisy family and are either annuals or short-lived perennials. Native to Mexico and parts of the United States, Indian blanket flowers. Large, daisy-like Indian blanket blooms frequently have two colors. These plants have basal rosettes of alternating leaves with serrated margins and hairy stalks. In Zones 2 to 11, Indian blanket flowers flourish in direct sunlight.

Indian Chestnut

Indian chestnut trees are sometimes known as purple bauhinia trees or orchid trees. These medium-sized, deciduous pea family trees are indigenous to India and Myanmar. In Zones 9 to 12, Indian chestnut trees flourish in the humid, tropical climate. Long, spherical leaves in the shape of a heart grow on Indian chestnut trees. Indian chestnut trees produce stunning blossoms with five thin petals in the late summer and into the late fall. A lovely scent emanates from these blossoms.

Indian Cress

Indian cress, also referred to as nasturtiums, is a vibrant, annual member of the Tropaeolaceae (nasturtium) family that grows quickly. Indian cress is a trailing plant that is native to areas of South America. In Zones 2 to 11, Indian cress is usually planted as an annual. These I-flowers produce broad, spherical leaves with noticeable cream veins. These leaves are complemented by unassumingly fragrant orange or crimson trumpet-shaped blooms. Flowers and leaves are both edible.

Indian Hawthorn

The rose family (Rosaceae) includes Indian hawthorn trees as evergreen shrubs and small trees. These lovely trees are indigenous to China, Japan, and a few other countries in Southeast Asia. Although the Indian hawthorn is mostly planted as an ornamental tree, it is occasionally utilized in bonsai. Indian hawthorn trees bloom in the spring with dense terminal clusters of tiny, fragrant pink or white flowers. Oblong leaves and appealing purplish-brown to grayish-brown bark are further features of Indian hawthorn, which also varies in age.

Frequently Asked Questions

What flowers start with the letter I?

Twenty-eight are covered here, including iris, impatiens, Iceland poppy, Iceberg rose, Inca lily, ixia, ixora, iberis, ipomoea, immortelle, indigo, ismene, ironweed, ivy, ivy geranium, ice plant, isotoma, incarvillea, Indian paintbrush, Indian blanket, Indian balsam, Indian hyacinth, Indian hawthorn, Indian cress, Indian chestnut, Indian breadroot, Italian bellflower and Inca marigold.

Why won’t my bearded iris flower?

Almost always because the rhizomes are planted too deep. They need to sit at the soil surface and bake in sun; burying them gives healthy leaves and no flowers. Overcrowding after several years has the same effect, so divide clumps every three to four years.

Are any flowers starting with I poisonous?

Several. Iris rhizomes are toxic and the sap irritates skin. Ipomoea seeds contain toxic alkaloids. Indian chestnut, like all horse chestnuts, is toxic. And Indian hyacinth (camas) is safe itself but grows alongside death camas, which is potentially fatal and looks very similar out of flower.

How do I stop Iceland poppies wilting in a vase?

Sear the cut stem end in a flame for a few seconds or dip it in boiling water. The milky sap otherwise seals the stem and blocks water uptake, which is why they collapse so quickly when simply cut and put in water.

Why did my impatiens suddenly die off?

Very likely downy mildew. Severe landscape outbreaks began in 2011 across Europe and North America and devastated Impatiens walleriana — leaves yellow, drop, and the plant collapses. New Guinea impatiens and bred-resistant strains are the practical replacements.

Is Himalayan balsam safe to plant?

No, and in several countries it is illegal to plant or allow it to spread. It out-competes native riverbank vegetation and leaves banks bare and eroding over winter. Its seed pods fling seed up to seven metres, and seed floats downstream and stays viable for about two years.

Sources

Himalayan balsam introduction date, seed dispersal distance and seed viability: Royal Horticultural Society and UK Wildlife Trusts guidance. Iceberg rose breeding and 1958 introduction: rose registration records. Impatiens downy mildew outbreak timeline: university extension plant-pathology sources. Death camas toxicity and zygacine: American Chemical Society; California Native Plant Society. Iris rhizome toxicity: standard toxicological plant references.

This article is for general information. Never eat any flower, bulb or root unless you are certain of its identification — camas and death camas are a genuinely dangerous pair.

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