Crocosmia is a small genus of flowering plants in the iris family, Iridaceae, placed in the order Asparagales. The genus comprises around nine accepted species of cormous perennials native to the grasslands of southern and eastern Africa, ranging from South Africa north to Sudan, with one species, C. ambongensis, endemic to Madagascar.
Plants grow from underground corms that form vertical chains, with the youngest corm at the top and the oldest buried deepest. Contractile roots on the lowermost corm actively pull it deeper into the soil. The chains are fragile and break apart easily — a trait that has allowed certain species and hybrids to spread aggressively beyond cultivation. Leaves are alternate, sword-shaped (ensiform), and parallel-veined, arising from the stem base. Inflorescences carry 4 to 20 vivid red or orange flowers arranged alternately on a branched, zigzag spike that arches horizontally. Flowers are hermaphroditic, with stamens of equal length and apically forked style branches. Pollination is carried out by insects, birds (particularly sunbirds), and wind. The fruit is a dehiscent capsule, shorter than wide.
The genus is perhaps best known through the garden hybrid Crocosmia × crocosmiiflora (montbretia), a cross between C. aurea and C. pottsii that has become naturalised — and in many regions invasive — across Europe, the British Isles, Australia, New Zealand, and parts of North America. More than 400 cultivars have been developed, and 24 cultivars held the Royal Horticultural Society's Award of Garden Merit as of 2023. Among the wild species, C. aurea (Falling Stars) is native across eastern and southern Africa and has naturalised in the Azores, while C. masoniorum (Giant montbretia) is prized by horticulturists for its bold, outward-facing flowers.
Etymology
The genus name Crocosmia derives from the Greek words krokos ("saffron") and osmē ("odour"), referring to the strong saffron-like scent released by the dried leaves when steeped in hot water. The widely used alternative name "montbretia" was coined by the French botanist Alire Raffeneau Delile in honour of Ernest Coquebert de Montbret, a fellow naturalist who accompanied Napoleon's Egyptian Campaign.
Distribution
Crocosmia is native to the grasslands of southern and eastern Africa, with the natural range extending from South Africa north to Sudan. One species, C. ambongensis, is restricted to Madagascar. Through cultivation and subsequent escape, C. × crocosmiiflora has naturalised widely and is now considered invasive in the United Kingdom, Ireland, Australia, New Zealand, the western United States, and several other regions.
Cultivation
Crocosmias are cultivated worldwide, with more than 400 named cultivars available. They are winter-hardy in temperate regions and thrive in well-drained soil in full sun to partial shade. Propagation is typically by division in spring — offsets are separated from the corm chains and replanted. Because corm chains are fragile and fragment readily, plants can spread beyond intended areas; in many temperate climates C. × crocosmiiflora cultivars require management to prevent invasive spread.
Propagation
The primary propagation method is division: corm offsets are lifted and separated in spring, then replanted at the appropriate depth. The naturally fragile corm chains mean that even routine lifting and dividing produces multiple propagules. Seed propagation is possible but less commonly used in cultivation.
