Dianella, commonly known as flax lily or blueberry lily, is a genus of roughly 40 accepted species of tufted, perennial rhizomatous herbs in the family Asphodelaceae (order Asparagales). Plants grow from fibrous or fleshy roots and produce clumps of narrow, strap-like or linear leaves. Aerial stems are mostly very short, occasionally elongated, and scaly or leafy at the base.
Flowers are bisexual and typically blue, purple, or white, arranged in loose, branched cymose inflorescences. Each flower bears three sepals that closely resemble the three petals, with a superior ovary. The ornamental fruit is a fleshy berry, characteristically bright blue to deep purple, though white-berried forms exist. Berries reach up to 1.5 cm in diameter.
The genus has a broad native range spanning southern and eastern Africa, Madagascar, the Mascarene Islands (Mauritius, Seychelles), tropical and subtropical Asia (including southern China and Southeast Asia), Australia, New Zealand, and islands of the Pacific Ocean including Hawaii, Fiji, and Samoa. Introduced populations are established in Florida and Jamaica. Approximately half of all species are native to Australia, where the genus occupies habitats from sandy soils near creeks to heaths and open woodlands.
Dianella is closely related to the genera Thelionema and Herpolirion within the broader asphodeloid clade. Some classifications have previously placed the genus in Hemerocallidaceae, though Asphodelaceae is now the accepted family placement.
Etymology
The genus name Dianella is a Latin diminutive of Diana, the Roman goddess of the hunt and the moon. The suffix -ella conveys smallness, giving the name the sense of "little Diana." The name was coined by the French botanist Jean-Baptiste Lamarck, who used it in his 1786 Encyclopédie Méthodique, though that publication lacked a valid formal genus description. Antoine Laurent de Jussieu later validated the name in his 1789 Genera Plantarum, which constitutes the accepted date of publication for the genus.
Distribution
The native range of Dianella extends from southern tropical Africa (Zimbabwe, Mozambique) and the Indian Ocean islands (Madagascar, Mauritius, Seychelles) eastward through South and Southeast Asia, southern China, the Malay Archipelago, and Papua New Guinea, continuing through Australia and New Zealand to the Pacific Islands, including Hawaii, Fiji, and Samoa. Introduced populations have naturalized in Florida and Jamaica.
Australia is the centre of diversity: over 25 species are recorded across all states, with at least 15 endemic. In eastern Australia, species such as Dianella caerulea, D. revoluta, D. longifolia, and D. tasmanica are widespread. New South Wales alone hosts numerous named species plus around five undescribed taxa. The wide-ranging Dianella ensifolia connects populations from southern Africa through tropical Asia to the Solomon Islands.
Ecology
Within Australia, Dianella species occupy a range of habitats. Many grow in sandy soils near creeks, in heaths, and in open or sparse woodlands. They tolerate both dry and moist soil conditions and persist in full sun as well as partially shaded understorey. Their rhizomatous habit allows them to form persistent ground-layer clumps and to colonise disturbed ground.
Cultivation
Dianella species and cultivars are widely grown as ornamentals for their attractive strap-like foliage and striking blue to purple berries. They perform best in well-drained, light sandy to loamy soils with neutral to mildly acidic pH, in a full-sun to lightly shaded position. They tolerate both dry and moist soils once established, making them adaptable garden plants.
In cool-temperate climates they are frost-tender; outdoor cultivation suits USDA hardiness zones 8–11 (UK zone 9), with a sunny, sheltered position and protection from hard frosts.
Propagation
Dianella can be propagated by seed or by division. For seed, pre-soaking in lukewarm water for 24 hours before sowing improves germination. Seeds sown in spring with gentle bottom heat germinate within one to three months at around 25°C. Seedlings are kept under greenhouse conditions for at least two years before transplanting outdoors in late spring or early summer.
Division is the more practical method for garden propagation. Established clumps are separated in spring; smaller divisions are potted into cold frames until they develop sufficient root systems, then planted out the following spring.
Cultural uses
Indigenous Australians have long used Dianella leaves for fibre and basketry — the tough, silky leaf fibres are worked into dillies (string bags) and woven baskets. Leaf fibre has also been extracted for textile use more broadly.
The berries are eaten in some cultures, raw or cooked, though their edibility is inconsistent across species. Reports range from toxic to palatable, with Dianella congesta regarded as having particularly sweet, nutty fruit. Given this variation in toxicity, identification to species level is important before any consumption.
Taxonomy notes
Dianella was first named by Lamarck in 1786 (as Diana Comm. ex Lam.), but that publication is treated as a heterotypic synonym because it lacked a proper genus diagnosis. The name Dianella Lam. ex Juss. was formally established in 1789 by Antoine Laurent de Jussieu in Genera Plantarum (Gen. Pl.: 41). The IPNI identifier is urn:lsid:ipni.org:names:24187-1.
The genus is placed in family Asphodelaceae, order Asparagales, class Liliopsida. An older treatment placed it in the segregate family Hemerocallidaceae, but Asphodelaceae is the currently accepted placement per POWO and GBIF. Dianella is most closely allied with the genera Thelionema and Herpolirion. Around 40 species are accepted by POWO, while GBIF recognises 72–76 descendant taxa under a broader concept. Over 25 species occur in Australia, at least 15 of them endemic.
