Astelia petriei

Basic Information

Common Name: Astelia petriei
Scientific Name: Astelia petriei
Native Habitat: Native to New Zealand, primarily found in alpine to subalpine tussock grasslands, rocky slopes, and fellfields of the South Island and Stewart Island. It typically grows in open, exposed sites at higher altitudes.

History / Discovery / Cultivator

The genus Astelia, part of the Asteliaceae family (sometimes included within the broader Asparagaceae or Liliaceae depending on taxonomic classification), comprises evergreen tufted perennial plants, many of which are endemic to the Southern Hemisphere, including New Zealand, Australia, and various Pacific Islands. The name Astelia is derived from the Greek word ‘asteles’, meaning ‘unsteady’ or ‘unfixed’, possibly referring to the rhizomatous root system or the dioecious nature of the flowers (male and female flowers on separate plants).

Astelia petriei was formally described by the British botanist Thomas Frederic Cheeseman (1846-1923). Cheeseman was a prominent figure in New Zealand botany, serving as the curator of the Auckland Museum for many decades and publishing significant works like the Manual of the New Zealand Flora (1906). His extensive field work throughout New Zealand, particularly in alpine and remote regions, led to the discovery and description of numerous plant species. The specific epithet ‘petriei’ honors Donald Petrie (1846-1925), another significant New Zealand botanist and school inspector who collected widely throughout the country and contributed greatly to the understanding of its flora, particularly alpine species. Petrie and Cheeseman were contemporaries and colleagues, often exchanging specimens and information. Cheeseman described Astelia petriei based on specimens collected by Petrie, recognizing it as distinct from other Astelia species known at the time, such as the more widespread Astelia nervosa or Astelia fragrans. The recognition of A. petriei as a separate species was based on its morphological characteristics, particularly leaf shape, texture, inflorescence structure, and its specific high-altitude habitat preference.

Historically, Astelia petriei was primarily known within scientific circles and to naturalists exploring the New Zealand mountains. Its role in traditional Māori use, unlike some other Astelia species (like A. nervosa, which was used for weaving or food), is less documented or significant due to its restricted, often remote, alpine habitat. Its tough, fibrous leaves and relatively sparse distribution at high altitudes likely made it less accessible or suitable for widespread harvesting compared to species found at lower elevations.

In terms of modern cultivation, Astelia petriei is not as commonly cultivated as some other Astelia species, which have gained popularity as architectural garden plants or even houseplants. Species like Astelia chathamica (Chatham Island Astelia) or cultivars like ‘Silver Spear’ are more readily available in nurseries. Astelia petriei, being adapted to harsh alpine conditions, can be challenging to grow in milder, lower-altitude garden settings or containers. It typically requires excellent drainage, cool temperatures, and exposure to significant light, replicating its native open, rocky or tussock environment. Cultivation, when attempted, is usually by specialist alpine gardeners or botanical gardens interested in New Zealand native flora. Propagation is primarily by division of established clumps or from seed, though seed germination can be slow and requires specific conditions, mimicking its natural alpine cycles. There aren’t specific cultivators widely associated with popularizing A. petriei in horticulture, rather it remains a plant of interest primarily to botanists, ecologists, and dedicated collectors of alpine flora.

Plant Care Summary

Botanical Insights

Adaptations

Astelia petriei exhibits several key adaptations that allow it to survive in the challenging alpine and subalpine environments of New Zealand. Its tough, leathery, linear leaves are covered in silvery or golden-brown hairs, which serve multiple purposes: reducing water loss through transpiration in exposed, windy conditions; providing insulation against cold temperatures; and reflecting intense UV radiation prevalent at high altitudes. The leaves form dense tussock-like clumps, which offer protection to the plant’s crown and root system from extreme cold, wind, and desiccation. The plant grows from a sturdy, often deep-seated rhizome, which anchors it firmly in rocky or unstable substrates and allows it to perennate through harsh winters, storing energy underground. Its ability to tolerate nutrient-poor, gritty soils is also crucial for survival in high-altitude environments where topsoil is often thin or absent. The plant is dioecious, meaning male and female flowers are on separate plants, relying on wind for pollination. The berries produced by female plants, though small, provide a food source for native birds, aiding seed dispersal in its often remote habitat.

Propagation Methods

The primary methods for propagating Astelia petriei are through division and from seed. Division is the most common and reliable method for established clumps, typically performed in spring or early autumn. Mature plants can be carefully lifted, and offsets or sections of the rhizome with established roots and shoots can be separated using a sharp knife or spade. Each division should have a healthy portion of roots and foliage. These divisions are then replanted immediately into well-drained soil. Propagating from seed is possible but requires patience and specific conditions. Seeds should be collected from ripe berries of female plants. The fleshy pulp should be removed, and the seeds sown in a gritty, well-drained seed mix. Germination can be erratic and slow, often requiring a period of cold stratification to mimic natural winter conditions. Seedlings grow slowly and may take several years to reach a significant size.

Toxicology

Based on available information, Astelia petriei, like other commonly cultivated Astelia species, is generally considered non-toxic to humans and common household pets like cats and dogs. While it’s always wise to prevent pets from chewing on plants, there are no widely reported cases or documented evidence suggesting that ingestion of Astelia petriei leaves or other parts causes significant toxic effects. Symptoms following accidental ingestion, if any, would likely be mild and transient, such as minor stomach upset, primarily due to mechanical irritation from the fibrous plant material rather than the presence of specific toxins. Therefore, it is generally regarded as a safe plant to have around pets and children, though consumption is not recommended.

Common Problems

Pests:

• Spider mites: Can sometimes affect indoor or greenhouse-grown plants, causing stippling on leaves.
• Scale insects: Infestations are rare but can occur, appearing as small bumps on stems and leaves.

Diseases:

• Root rot: The most significant issue, caused by poor drainage and excessive moisture, leading to wilting and plant death.

Other:

• Leaf yellowing: Often a sign of overwatering, poor drainage, or sometimes nutrient deficiency in poor substrates.
• Browning leaf tips/margins: Can indicate underwatering, low humidity in dry indoor environments, or exposure to harsh winds and cold.
• Lack of vigour/slow growth: Typically due to insufficient light, incorrect soil type, or attempting to grow the plant in conditions too warm or humid for its alpine nature.
• Failure to thrive in cultivation: Usually results from failure to provide the essential conditions of excellent drainage, cool temperatures, and open, exposed light conditions.

Rarity & Value

Rarity:

Astelia petriei is not considered critically endangered in the wild within New Zealand, but it is not as common or widespread as some other Astelia species. Its rarity in cultivation is significant because it is challenging to grow outside of specific, cooler, well-drained conditions that mimic its native alpine habitat. It is not a plant readily found in standard garden centres and is typically only available from specialist native plant nurseries or growers focused on alpine flora. Factors contributing to its cultivated rarity include its slow growth rate from seed, the specific environmental conditions it requires, and lower horticultural demand compared to more ornamental or adaptable Astelia cultivars.

Value:

The market value of Astelia petriei specimens is influenced less by common horticultural trends and more by its status as a specific New Zealand native alpine plant. Factors affecting value include:

• Size and Maturity: Larger, well-established clumps are more valuable as they represent years of growth.
• Provenance: Plants sourced from reputable native plant nurseries or those with documented wild origin (ethically sourced) might be valued differently.
• Form and Colour: Specimens exhibiting characteristic dense tussock form and desirable silvery-golden leaf colouration are preferred.
• Availability: Its general rarity in cultivation means that when available, specimens may command a higher price than more common Astelia varieties. It is primarily valued by collectors of native New Zealand flora and alpine plant enthusiasts.