Myoporum montanum R.Br.

Nomenclature and Growth Form

Myoporum montanum R.Br., commonly called waterbush, is a glabrous shrub or small tree that grows up to 8 metres (30 ft) tall.

Similar Species Taxonomic History

This species is hard to distinguish from Myoporum acuminatum, and their distribution ranges overlap; George Bentham originally classified M. montanum as a variety of Myoporum acuminatum.

Similar Species Distinguishing Features

M. montanum can be told apart from M. acuminatum by its smaller, narrower leaves, sepals that lack the translucent margins found on M. acuminatum sepals, and pink or light purple fruit compared to the dark purple or blue fruit of M. acuminatum.

Leaf Shape and Venation

Waterbush leaves vary in shape, but are most often thin, linear to elliptic, gradually tapering to a tip, with the mid-vein visible only on the lower surface.

Leaf Size and Texture

Leaves are typically 45–100 millimetres (2–4 in) long and 5–21 millimetres (0.2–0.8 in) wide, glabrous, the same colour on both sides, and have smooth edges.

Inflorescence Structure

Sweet-scented flowers grow in clusters of 1 to 5 from leaf axils, on stalks 4.5–11 millimetres (0.2–0.4 in) long.

Sepal Characteristics

There are 5 egg-shaped to triangular sepals with slightly papery margins that are only translucent near their base.

Petal Coloration and Count

Flowers usually have five (rarely six) white petals, which are occasionally light pink or purple, and may bear rows of purple spots.

Petal Tube and Lobes

Petals form a tube 2–5 millimetres (0.08–0.2 in) long, with lobes around the same length as the tube.

Open Flower Diameter

The total diameter of an open flower is around 6–8 millimetres (0.2–0.3 in).

Flowering Period and Fruiting Onset

Flowering occurs mostly in winter and summer, and is followed by the development of smooth or slightly rough drupe fruits.

Drupe Size and Color

Drupes are ovoid in shape, 5–8 millimetres (0.2–0.3 in) in diameter, and coloured light purple, red purple or brown.

Fruit Tip Feature

A remnant of the flower style protrudes from the tip of the fruit.

Intraspecific Forms

Robert Chinnock recognised three distinct forms of this species: the Type form from the Blue Mountains, which has narrow, linear leaves and small flowers that are only faintly spotted, if at all; the Desert form from arid areas of Australia, which is a large shrub or small tree with thick, elliptic leaves and prominently purplish red-spotted flowers; and the Tropical form from northern Australia, New Guinea and Timor, which has thin leaves and very small, unspotted white flowers.

Distribution Range

Waterbush occurs in all mainland states of Australia, with scattered populations in New Guinea and Irian Jaya, and a single recorded occurrence from Timor.

Common Population Locations

It is very common in eastern Queensland, New South Wales and eastern South Australia.

Habitat and Soil Range

It grows in a wide range of ecosystem types, from mangrove swamps to rainforest to the Simpson Desert, across a broad range of soil types.

Peripheral Habitat Restrictions

Outside of its common Australian range, occurrences across the rest of the continent, New Guinea and Timor are mostly restricted to coastal regions, watercourses and other locations with more reliable water access.

Fruit Consumers

The fruit of Myoporum montanum is a food source for many bird species, including emus, and was historically eaten by Aboriginal people.

Fruit Toxicity and Nutritional Value

The food value of the fruits is rated as low, and some species in this genus are known to contain liver toxins.

Fruit Flavor Profile

The flavour is described as "bitterly aromatic and salty sweet".

Horticultural Drought Tolerance

In horticulture, waterbush is a hardy cultivated plant that tolerates drought.

Horticultural Use and Propagation

It makes a useful screen plant for drier sites, and is easily propagated from cuttings.