Flax Lily

Basic Information

Common Name: Flax Lily
Scientific Name: Dianella caerulea
Native Habitat: Eastern Australia (Queensland, New South Wales, Victoria, Tasmania). Found in a variety of habitats including woodlands, forests, coastal areas, and open heathlands.

History / Discovery / Cultivator

Dianella caerulea, commonly known as the Flax Lily, is a resilient and widespread perennial plant native to the eastern regions of Australia. Unlike many plants whose histories are tied to specific European explorers or botanists who “discovered” them for Western science, the Flax Lily holds a long history of interaction with the Indigenous peoples of Australia, who were intimately familiar with its properties and uses for thousands of years before European settlement. The strappy leaves were traditionally used for weaving baskets and cordage, demonstrating its practical value to early inhabitants. Some reports also suggest the rhizomes were a source of food, although the extent of this use specifically for Dianella caerulea varies by source and region.

The genus Dianella was formally described by the French botanist Jean-Baptiste Lamarck in 1783, with Dianella caerulea being one of the species later catalogued and described within this genus as botanists explored the diverse flora of Australia. Its scientific name, caerulea, refers to the blue colour often found in its berries or sometimes its flowers. As European settlement progressed and horticulture developed in Australia and beyond, the toughness and adaptability of Dianella caerulea became increasingly recognised.

It wasn’t a single cultivator or event that popularised the Flax Lily, but rather its inherent resilience and attractive features that led to its gradual adoption in gardening and landscaping. Its ability to thrive in a wide range of conditions – from full sun to partial shade, and in various soil types – made it a valuable plant for gardeners seeking low-maintenance options. As interest in native Australian plants grew, Dianella caerulea became a staple, valued for its evergreen foliage, architectural form, delicate blue flowers, and decorative blue berries.

In modern horticulture, Dianella caerulea is widely cultivated not only in Australia but also in other regions with suitable climates. Numerous cultivars have been developed or selected for specific traits, such as different foliage colours (including variegated forms), compact growth habits, or enhanced flowering/fruiting. These cultivars, alongside the species form, are popular choices for mass planting, borders, containers, and erosion control, testament to the enduring appeal and practicality of this native Australian plant. Its history in cultivation is less about a dramatic discovery and more about the steady recognition of its ecological importance and ornamental value.

Plant Care Summary

Botanical Insights

Adaptations

Dianella caerulea is a highly adaptable plant, which accounts for its wide distribution across various habitats in eastern Australia. One of its key adaptations is its robust, rhizomatous root system. This network of underground stems allows the plant to spread vegetatively, form dense clumps that prevent erosion, and store water and nutrients, making it highly tolerant of dry periods and fluctuating soil conditions. The strappy, linear evergreen leaves are also adapted to reduce water loss through transpiration, particularly in sunny or windy environments. The production of small, often blue, berries after flowering serves as a mechanism for seed dispersal, attracting birds that consume the fruit and spread the seeds. Its ability to thrive in both full sun and partial shade demonstrates its flexibility in adapting to different light availability across its diverse native range.

Propagation Methods

The most common and effective method for propagating Dianella caerulea is by division. Mature clumps can be carefully dug up, and the rhizomatous root ball can be divided into smaller sections, each containing roots and foliage. These divisions can then be replanted directly into the ground or pots. This method ensures the new plants are clones of the parent and reach maturity relatively quickly. Propagation by seed is also possible, though it can be slower and results in greater genetic variability. Seeds are typically found within the mature blue berries. They should be cleaned, and germination can sometimes be erratic or require specific conditions, such as scarification or stratification, depending on the source and freshness of the seed.

Toxicology

Dianella caerulea is generally considered to have low toxicity. The primary concern, if any, would be accidental ingestion of the berries. While sources vary, most indicate that the blue berries are not significantly toxic to humans or common pets like cats and dogs. Some Australian native plant resources state the ripe berries are edible, while others advise against raw consumption or note they are not palatable. Symptoms from ingestion, if they occurred, would likely be mild gastrointestinal upset due to indigestibility or minor irritants. The fibrous leaves are not appealing and pose no significant toxicity risk if chewed, beyond potential mechanical irritation. Overall, Dianella caerulea is not listed among plants with significant toxic concerns for pets or humans.

Common Problems

Pests:

• Generally pest-resistant.
• Occasionally susceptible to aphids or mealybugs, especially on stressed plants or in sheltered environments.

Diseases:

• Generally disease-resistant.
• Root rot is the most common problem, caused by poor drainage and excessive soil moisture.
• Leaf spot diseases are rare but can occur in very humid or poor air circulation conditions.

Other:

• Browning leaf tips: Most often caused by underwatering, low humidity, excessive sun exposure, or exposure to harsh winds.
• Lack of flowering/fruiting: Usually due to insufficient light, particularly in heavily shaded positions. Also, young plants may not flower until they reach maturity.
• Pale or yellowing leaves: Can indicate nutrient deficiency (though rare as it’s low-feeding), or sometimes excessive watering.

Rarity & Value

Rarity:

The species Dianella caerulea itself is not considered rare. It is a common, widespread, and ecologically significant plant throughout its native range in eastern Australia. It is readily available in nurseries due to its ease of cultivation and popularity in landscaping. However, certain specific cultivars of Dianella caerulea, such as those with unique variegation (‘Little Jess’, ‘Cassa Blue’, ‘Kingston Emerald’ are common cultivars, but less common or newly released variegated forms might be harder to find) or particularly compact habits, might be less common in the general market depending on availability from specialist growers or current popularity trends. But the basic species form is abundant.

Value:

The market value of Dianella caerulea is typically modest compared to highly sought-after collector plants, primarily because the species form is so common and easy to propagate. Factors influencing the value include:

• Size and Maturity: Larger, well-established clumps command a higher price than small tube stock or young plants.
• Cultivar: Specific cultivars, particularly those with stable and attractive variegation or desirable growth habits, are often more expensive than the base species.
• Provenance: Plants from reputable nurseries or those known to be healthy and well-grown may have a slightly higher value.
• Current Demand: As a popular landscaping plant, demand generally affects pricing, but its widespread availability keeps prices relatively stable and affordable for the common varieties. Rare or newly released variegated forms can occasionally fetch higher prices among collectors.