Common Heath

Appearance

''Epacris impressa'' grows as a woody shrub with an erect habit, sometimes reaching 2 to 3 m in height although plants in the range of 0.5 to 1 m tall are more commonly observed.

The branches are stiff and have small leaves with prickly, pointed apices that are 8–16 mm long. The flowers mainly occur between late autumn and early spring, arising in dense and sometimes pendulous clusters along the stems. White, pink or red in colour, they are 1–2 cm and are narrow and tubular with five indentations on the base.

The corolla of the flower is formed by five petals, fused at the base to form a tubelike structure, with the free petal ends forming five lobes at the apex. There are five whorled sepals at the base of the corolla. Within the corolla is a central style that persists through development of the fruit. The style connects the stigma at the apex and ovary at the base, where the nectar is also located. Different colour forms are often observed growing near each other.

The fruit is a 5-locule capsule that is about 3.5 mm in diameter. It is globular in shape, sometimes with one end flattened. Initially green, it dries and splits, releasing numerous tiny seeds.

Naming

French botanist Jacques Labillardière collected the species in 1793 and described it in 1805. Four forms have been identified, but no subspecies are recognised.

Distribution

''Epacris impressa'' is commonly found in coastal regions and nearby foothills, ranging from Kangaroo Island and the southern Mount Lofty Ranges in South Australia across southern Victoria, extending to the Grampians and the Little Desert, and northwards to southern New South Wales as far as the Clyde River in the Budawang Range. It is also widespread in Tasmania. Plants are recorded at altitudes up to 1,200 metres at Mount Stradbroke and Mount Tingaringy in East Gippsland. The species grows in widely diverse habitats including sand and clay heathland, herb-rich and heathy woodland, lowland and shrubby dry forests, riparian thickets, montane rocky shrubland and rocky outcrops.

Habitat

Honeyeaters such as the eastern spinebill are attracted to the flowers. As the bird gathers the nectar, the pollen, which has fins, attaches itself to the feathers on the heads of the birds and is carried to other flowers, aiding cross pollination. A study in forests near Hobart in Tasmania found that the eastern spinebill arrived in the area at the same time the common heath was in flower in March, and left once flowering had finished. Other honeyeaters, such as the strong-billed, crescent and yellow-throated honeyeaters, fed occasionally at common heath flowers. Field work in the Mount Lofty Ranges in South Australia recorded the white-plumed and New Holland honeyeaters, as well as the crescent honeyeater and the eastern spinebill.

Insects recorded visiting white-flowered plants include the Australian painted lady and yellow admiral , as well as bees. Field work in southern Tasmania showed that the introduced bumblebee sometimes robbed nectar by piercing the base of the tube. This then allowed honeybees to retrieve nectar the same way. ''Epacris impressa'' is host to the scale insect ''Lecanodiaspis microcribraria''.

A field study of the invasion of the pathogen ''Phytophthora cinnamomi'' into the Brisbane Ranges National Park in Victoria in 1971 indicated that ''Epacris impressa'' was moderately susceptible to the pathogen. Inoculation of seedlings confirmed this. Fieldwork in the Brisbane Ranges National Park in 1985 showed that there was some evidence that ''E. impressa'' seedlings were able to recolonise areas that had been infested with ''P. cinnamomi'' a decade before.

''Epacris impressa'' regenerates after bushfire by seed and resprouting. Fieldwork in heathland in the Otway Ranges in the years following the 1983 Ash Wednesday bushfires showed that large numbers of ''E. impressa'' seedlings appeared in some areas, and that flowering took place as early as the second year after the fire.

The roots of ''Epacris impressa'' are colonized by fungi forming ericoid mycorrhiza. It is believed that the fungal species vary between regions.

Uses

A highly regarded garden plant, the common heath was first cultivated in England in 1825 with over seventy named cultivars, most of which have now vanished. A pink-flowered form, often referred to as "pink heath", is the floral emblem of the state of Victoria. ''Epacris impressa'' has proven a difficult plant to propagate reliably, which has limited its use in horticulture and revegetation. It grows best in well-drained but moist soil in a semishaded position.