Myoporum insulare: The All-round Brilliant Common Boobialla

Overview

Myoporum insulare, commonly known as the common boobialla or coastal boobialla, is an unusual, hardy, all-round evergreen that can fast establish as a ground cover, spreading shrub, or small tree.

This plant is well known for its ability to thrive in coastal conditions, making it an excellent choice for erosion control and landscaping in coastal regions. It also spreads in inland environments in southern Australia.

With its dense foliage, attractive white flowers, and edible purple berries, Myoporum insulare is a versatile plant offering aesthetic and ecological benefits.

Origin and distribution

Myoporum insulare is endemic to the mid to southern coastlines of Australia. It is often found in coastal dunes, rocky shores, cliffs, and heathlands.

While it often occurs as a coastal plant in warm, cool temperate, and mild subtropical zones, it also flourishes in drier Mediterranean climate regions.

With an exceptional adaptability, Myoporum insulare has also been cultivated worldwide, particularly in regions with similar climates. However, in some countries, it has become an invasive species that demands serious attention.

Growth and care

Myoporum insulare thrives in various climates, from temperate to Mediterranean regions. It is drought-resistant once established and can tolerate light frost but does not perform well in prolonged freezing conditions.

A strong attribute is its ability to thrive in exposed coastal conditions. It is highly tolerant of salt spray, strong salt-laden winds, and nutrient-poor saline soils that may hinder the growth of other native species.

It can also adapt to various soil types, including light sand and heavy clay. This plant can tolerate periodic wetness and boggy conditions, although it does not sustain consistent waterlogging.

Myoporum insulare does particularly well in alkaline soils like limestone soils in its coastal habitat. It also flourishes in common soils with slightly acidic to neutral pH.

As a low-maintenance plant, it requires minimal care. This plant responds well to pruning, which can be performed year-round to maintain its size and shape without affecting flowering or fruiting.

Regular pruning can also encourage dense and compact growth. Cuttings of hardened branchlets strike readily in the ground to form new plants.

Myoporum insulare is highly adapted to nutrient-poor soils and does not require heavy fertilisation. However, adding organic matter, like compost, at planting can be beneficial. Lightly applying a balanced fertiliser may boost growth during the growing season.

Myoporum insulare cultivars

The original Myoporum insulare can reach 6 meters tall in optimal conditions. While this height is ideal for tall screening and windbreaks, regular upkeep is required to keep this plant low and compact.

Several varieties only grow to a limited height for desired purposes:

• ‘Ground Hug’: An effective groundcover that grows to about 10 – 20 cm in height with a 4-meter spread, with a flat, dense growth pattern similar to Myoporum parvifolium.
• ‘Coastal Carpet’: Another compact groundcover variety with more oblong foliage, 20 cm in height and 1 m in width at maturity.
• ‘Prostrate’: A low-spreading bush with a prostrate habit and mounded form that can reach about 40 – 50 cm in height and 2 meters wide.
• ‘Compact’: A fast-growing shrubby variety that can reach 2.5 meters in height and 2 meters in width.

Features

Naturally occurring Myoporum insulare often adopts a form of a spreading shrub or stout, erect tree. With different cultivars available, it can be cultivated to suit various landscape needs.

The foliage of Myoporum insulare is attractive, lance- or spear-shaped, thick, and glossy green, providing a lush appearance throughout the year. The plant’s dense foliage and spreading habit are highly valuable as a ground cover, shrub, or tree.

Myoporum insulare develops a shallow, sprawling root system to cope with its habitat environment. While it spreads as a ground cover or prostrate shrub, it sends out root runners that can potentially form new plants. Root runners can be separated into cuttings, allowing this plant to be propagated easily.

Its ability to spread is highly desirable for soil stabilisation. However, this also means it can quickly colonise an area, resulting in its invasiveness.

The plant features small white flowers with purple spots. These flowers emerge in clusters at the base of the leaves in spring and summer. Fleshy, smooth, round, and purple fruits follow.

Landscape uses

• Hedging and screening: The dense foliage provides excellent privacy screening and hedging with regular pruning.
• Windbreaks: When growing in optimal conditions, the plant can be grown tall, providing effective windbreaks.
• Ground cover: The low-growing cultivars are highly effective as a ground cover, a suitable lawn substitute or weed suppressant for low foot traffic areas.
• Erosion control: Its ability to spread, extensive root system, and dense foliage are perfect for erosion-prone sites.
• Coastal garden: Its high tolerance in exposed coastal conditions makes it ideal for seaside gardens.
• Land restoration: Its rapid spread and low-maintenance nature make it highly useful in land restoration projects when quick revegetation is the priority.
• Specimen plant: Myoporum insulare can be grown as a feature bush or tree to showcase its lush foliage and rounded form.
• Container and retaining wall: Its prostrate growth is highly suitable for container and retaining wall edge plantings.
• Shade tree: As a fast-growing plant with dense growth, it can be trained as a canopy tree, providing welcoming shade.
• Wildlife habitat: Birds consume its fruit and use its foliage as shelter.
• Bush food: Edible fruits can be used to make jams and other preserves.