Epacris impressa
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Epacris impressa, also known as common heath, is a species of plant in the heath family Ericaceae. It is native to south-eastern Australia (the states of Victoria, Tasmania, South Australia and New South Wales). French botanist Jacques Labillardière collected the species in 1793 and described it in 1805. Four forms have been identified, but no subspecies are recognised. Growing in heathland, shrubland or open forest, it is generally a small shrub around Template:Convert tall, with small stiff leaves. The red, pink or white tube-like flowers appear from late autumn to early spring. Honeyeater birds, particularly the eastern spinebill, feed upon the nectar of the flowers. It regenerates after bushfire by seed or by resprouting.
A highly regarded garden plant, the common heath was first cultivated in England in 1825; over seventy named cultivars have been developed, 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.
Description
[edit]Epacris impressa grows as a woody shrub with an erect habit, sometimes reaching Template:Convert in height although plants in the range of Template:Convert tall are more commonly observed. The branches are stiff and have small leaves with prickly, pointed apices that are Template:Convert 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 Template:Convert and are narrow and tubular with five indentations on the base.<ref name=Corrick>Template:Cite book</ref><ref name=APNI23924>Template:APNI</ref> 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.<ref name="Bailey88"/><ref name=eflorasa/> The style connects the stigma at the apex and ovary at the base, where the nectar is also located.<ref name="Bailey88">Template:Cite journal</ref> Different colour forms are often observed growing near each other.<ref name=Viridans>Template:Cite book</ref> The fruit is a 5-locule capsule that is about Template:Convert in diameter.<ref name=eflorasa/><ref name=RBG8623>Template:Cite web</ref><ref name=NSW>Template:Cite web</ref> It is globular in shape, sometimes with one end flattened.<ref name=eflorasa/> Initially green, it dries and splits, releasing numerous tiny seeds.<ref name=eflorasa/><ref name=Elliot>Template:Cite web</ref><ref name=ANBG/>
Taxonomy
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The type specimen of common heath was collected in 1793 by French botanist Jacques Labillardière in Van Diemen's Land (now Tasmania) during a voyage with Antoine Bruni d'Entrecasteaux. Labillardière described it in his 1805 work Novae Hollandiae Plantarum Specimen, giving it its current name Epacris impressa.<ref name=APNI23686>Template:APNI</ref> The Latin specific epithet impressa (meaning "impressed" or "indented") alludes to the indentations on the floral tube.<ref Name=ANPSA>Template:Cite web</ref> The original mounted specimen is currently held at the National Herbarium of Victoria at the Royal Botanic Gardens, Melbourne.<ref Name=ABC>Template:Cite web</ref>
A number of specimens once described as separate species are now regarded as Epacris impressa, with no recognised subspecies.<ref name=APNI23686/> Scottish botanist Robert Brown described Epacris ruscifolia in his 1810 work Prodromus Florae Novae Hollandiae et Insulae Van Diemen alongside E. impressa.<ref name="R.Br. 1810">Template:Cite book</ref><ref name=APNI25612>Template:APNI</ref> John Lindley described Epacris tomentosa from plant specimens collected during the third expedition of Thomas Mitchell in 1838. Upon encountering Epacris impressa on Mount William in the Grampians, Mitchell remarked that it was "A most beautiful downy-leaved Epacris with large, curved, purple flowers, allied to E. grandifloraTemplate:Refn but much handsomer".<ref>Template:Cite book</ref> Dr Robert Graham described Epacris ceriflora (which he spelt ceraeflora) from plants cultivated at the Edinburgh Botanic Gardens in 1832. The seed had come from Tasmania, the resulting progeny flowering over April and May 1832.<ref>Template:Cite journal</ref> A year later, he described E. nivalis, which he called an "exceedingly beautiful species", from specimens growing in Loddiges nursery. He also noted a form with long corollas that had been called E. variabilis that was in cultivation at the time, and noted it was difficult to describe the precise characteristics that distinguished E. ceraeflora, E. nivalis, E. variabilis and E. impressa.<ref>Template:Cite journal</ref>
In his landmark Flora Australiensis (1869), George Bentham argued that several previously described species were in fact a single species – E. impressa,<ref name="Bentham 1869">Template:Cite encyclopedia</ref> uniting E. variabilis, a short red-flowered E. campanulata, E. ruscifolia, which had narrow leaves and long flowers, the white-flowered E. nivalis, and short white-flowered E. ceraeflora. He re-classified as a separate species – E. reclinata – several plants that Allan Cunningham had collected in the Blue Mountains and classified as E. impressa.<ref name="Bentham 1869"/>
In the same work, Bentham named and described two naturally occurring varieties, Epacris impressa var. grandiflora and E. impressa var. ovata.<ref name=StaceI/> Plant specimens designated as grandiflora had been collected in the Wimmera, the Grampians (including those previously designated as E. tomentosa) and at Stawell in Victoria. Those classified as ovata were collected at Twofold Bay and Mount Imlay in southeastern New South Wales as well as Woolnorth and Rocky Cape in northern Tasmania.<ref name=APNI23924/><ref name=APNI24101>Template:APNI</ref> Bentham noted that, although variable, all forms had "five impressed cavities outside, alternating with the stamens immediately above the ovary."<ref name="Bentham 1869"/>
In his 1972 publication A Handbook to Plants in Victoria, Australian botanist Jim Willis expressed his view that dividing the species into subspecies was not feasible given that common heath is highly variable in flower colour and leaf shape, though he conceded the Grampians race grandiflora might be distinctive based on its larger corollas and coarser and hairier foliage.<ref name=StaceI/> Currently, both grandiflora and ovata are regarded as synonyms of Epacris impressa rather than being classified as distinct varieties.<ref name=APNI23924/><ref name=APNI24101/> The plant populations that best fit Bentham's original description of grandiflora, also known as Grampians heath, occur naturally on sandstone at locations including Mount Zero, Mount Stapylton and the Black Range.<ref name="Cochrane 1980"/><ref name=RBG/> Other nearby populations are regarded as having intermediate characteristics, including those in the Victoria Range and Mount Arapiles.<ref name=RBG>Template:Cite web</ref> Although not recognised in the Australian Plant Census, the variety is noted as "rare" on the list of Advisory List of Rare or Threatened Plants in Victoria issued by the Department of Environment and Primary Industries.<ref name=APNI23924/><ref name=DEPI>Template:Cite web</ref>
Variation in flower colour and length
[edit]In 1977 Helen Stace and Yvonne Fripp from La Trobe University studied 195 populations of Epacris impressa in Victoria, South Australia and Tasmania and found that 120 consisted of mixed stands of two or more races while 75 populations were of one race only. They identified four races based on the following corolla characteristics:<ref name=StaceI/>
- white-flowered with a markedly shortened corolla that is Template:Convert long and red-purple anthers,<ref name=StaceI/> usually found in sites with greater sun exposure.<ref name=StaceII/> Occurring throughout the species range,<ref name=StaceI/> this form is the most widely distributed.<ref name=StaceII/>
- pink-flowered, with a longer corolla that is Template:Convert long and cream-white anthers, in more shaded sites.<ref name=StaceII/> This form occurs throughout the species range.<ref name=StaceI/> Field work in Victoria and Tasmania found that pink-flowered plants in mixed populations often have pink or red anthers.<ref name=StaceIII>Template:Cite journal</ref>
- long scarlet race, with orange-red flowers and corolla Template:Convert long and cream-white anthers. Those from the granitic mountains of Wilsons Promontory and near W Tree in East Gippsland in Victoria flower between April and November. Other localities where this race has been recorded include the Howe Ranges and Clyde Mountain in New South Wales.<ref name=StaceI/>
- broad pink or white, the grandiflora race from the Grampians and Mount Arapiles in Victoria. Plants of this race are taller, often reaching Template:Convert in height. White or pink colour bear no relation to corolla length. Plants from Mount Arapiles are always pink-flowered.<ref name=StaceI/>
The long-pink and short-white races frequently occur in close proximity to each other; in these mixed populations the former tends to flower in winter and the latter in spring.<ref name=StaceI>Template:Cite journal</ref><ref name=StaceII>Template:Cite journal</ref> The question has been raised whether these different forms are becoming incompatible. However, controlled cross-pollination between plants with short and long corollas showed that there was no incompatibility between them.<ref name=Obrien89>Template:Cite journal</ref>
Pink-flowering populations have a relatively distinct genetic makeup, whereas red or white flowering populations have more evident sharing of genetic traits.<ref name=Conomikes>Template:Cite report</ref> Research based on DNA profiling has revealed substantial genetic diversity within and between flower colour races and site populations. This has implications for vegetation projects in that provenance material needs to be collected from a wide geographic area to maintain this diversity.<ref name=Conomikes2012>Template:Cite journal</ref>
Distribution
[edit]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.<ref name=eflorasa>Template:Cite web</ref><ref name=NSW/><ref Name=ANBG/> It is also widespread in Tasmania.<ref name=key>Template:Cite web</ref> Plants are recorded at altitudes up to Template:Convert at Mount Stradbroke and Mount Tingaringy in East Gippsland.<ref name="Cochrane 1980">Template:Cite book</ref> 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.<ref name=EVC>Template:Cite web</ref><ref name=WPB>Template:Cite web</ref>
Ecology
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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.<ref Name=PV>Template:Cite web</ref> 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.<ref>Template:Cite journal</ref> 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.<ref>Template:Cite journal</ref>
Insects recorded visiting white-flowered plants include the Australian painted lady (Vanessa kershawi) and yellow admiral (V. itea), as well as bees.<ref name=StaceII/> Field work in southern Tasmania showed that the introduced bumblebee (Bombus terrestris) sometimes robbed nectar by piercing the base of the tube. This then allowed honeybees (Apis mellifera) to retrieve nectar the same way.<ref>Template:Cite journal</ref> Epacris impressa is host to the scale insect Lecanodiaspis microcribraria.<ref>Template:Cite book</ref>
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.<ref>Template:Cite journal</ref> Inoculation of seedlings confirmed this.<ref>Template:Cite journal</ref> 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.<ref>Template:Cite journal</ref>
Epacris impressa regenerates after bushfire by seed and resprouting.<ref name=Wark-White-et-al.-1987>Template:Cite journal</ref><ref name=Molnar-Fletcher-Parsons-1989>Template:Cite journal</ref> 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.<ref name=Wark-White-et-al.-1987/>
The roots of Epacris impressa are colonized by fungi forming ericoid mycorrhiza. It is believed that the fungal species vary between regions.<ref name="McLean & Lawrie 1996">Template:Cite journal</ref>
Cultivation
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Propagated from seed collected by William Baxter in southern Australia, common heath was introduced into cultivation in England by the Clapton Nursery in 1825.<ref name="Paxton 1836">Template:Cite book</ref> Due to its frost-tenderness, it was mostly restricted to greenhouse cultivation.<ref name=ANBG/> In 1873, a variety known as Epacris impressa alba was recorded as being grown commercially for cut flowers in Boston in the United States.<ref name=Harding>Template:Cite journal</ref> While initially popular – over seventy cultivars appeared in the literature at the time – most have since disappeared.<ref name=EJ84>Template:Cite book</ref>
Plants grow best in a moist but well-drained, acidic soil,<ref Name=ANBG/> with added peat being helpful.<ref name="Marriott88">Template:Cite journal</ref> They may be grown in coastal gardens in a sheltered position,<ref name=Greig>Template:Cite book</ref> and generally require some degree of shade. Once established, plants can tolerate short dry spells.<ref name=EJ84/> As they age, plants may become straggly, but benefit from hard pruning after fertilizing and watering, which promotes compact, bushier growth. Common heath can be short-lived and difficult to transplant,<ref name="Marriott88"/> though it can be readily grown as a pot plant.<ref name=EJ84/> Along with other members of the genus, Epacris impressa initially proved difficult to grow and maintain on original soil in the Australian National Botanic Gardens in Canberra.<ref name="Butler84">Template:Cite journal</ref>
Propagation both by seed and cuttings is difficult, reducing potential production by plant nurseries. Germination rates of soil-stored seeds have been found to increase substantially with the application of heat and aqueous solutions of smoke.<ref name="Enright 2001">Template:Cite journal</ref> The most satisfactory results from cuttings can be achieved by using tip growth, taken six weeks after the cessation of flowering, and kept under a fogging system for twenty weeks.<ref name=Conomikes/> Plantsman Neil Marriott recommends semi-hardened cutting material taken in spring and autumn.<ref name="Marriott88"/> Roots of cuttings are brittle and easily damaged.<ref name="Marriott88"/>
Cultivars
[edit]The following forms have been selected and grown for cultivation:
- 'Bega'
This is a form from Bega in southern New South Wales that has bright red flowers and grows to Template:Convert high. It is regarded as one of the more reliable forms in cultivation.<ref name=ANPSA/><ref name=austraflora/> White- and pink-flowered forms from the same region also have horticultural potential.<ref name="walters88">Template:Cite journal</ref>
- 'Cranbourne Bells' and other double-flowered forms
'Cranbourne Bells' is a double-flowered form with pink flower buds fading to white as they open.<ref Name=ACRA1>Template:Cite web</ref> Registered by the Australian Cultivar Registration Authority in 1988, it occurred naturally near the Royal Botanic Gardens Cranbourne in Victoria, but its habitat has since been cleared.<ref Name=ACRA1/><ref name=SGAP>Template:Cite book</ref> A double-flowered form of Epacris impressa was collected as early as the 1860s in Victoria when Government Botanist Ferdinand von Mueller sent a specimen to Kew Gardens. This was examined by botanist William Hemsley in 1865. The specimen, labelled as Epacris impressa var. pleniflora, originated from Stawell in western Victoria.<ref name="B&F 1865B">Template:Cite journal</ref><ref name="B&F 1865A">Template:Cite journal</ref><ref name="B&F 1917">Template:Cite journal</ref> Another specimen given the same name by Mueller was collected at Nunawading, today a suburb of Melbourne.<ref name=Mueller>Template:Cite journal</ref> Charles French, co-founder of the Field Naturalists Club of Victoria, collected a white double-flowered form from Cheltenham south of Melbourne in 1859 and a pink double-flowered form from Dromana on the Mornington Peninsula in about 1862. These were later sent as rooted cuttings to Veitch Nurseries in England.<ref name=French>Template:Cite news</ref> Double-flowered forms of various colours have since been found throughout Victoria, but only single plants have been observed in any location, and they are still regarded as a rarity.<ref name="Clifford 1949">Template:Cite journal</ref> A naturally occurring form of the variety grandiflora with rosebud-like double flowers is also grown.<ref name=EJ84/><ref name=austraflora>Template:Cite book</ref>
- 'Spring Pink'
A form with deep pink flowers on long spikes, 'Spring Pink' appears in spring. It grows to Template:Convert high.<ref name=austraflora/>
Floral emblem of Victoria
[edit]In 1951, at a meeting of representatives of government and other bodies, it was agreed that the pink form of the common heath, the "pink heath", be adopted as the official floral emblem for the state of Victoria.<ref Name=ANBG/> Victoria was the first Australian state to adopt a floral emblem.<ref Name=ANBG>Template:Cite web</ref> The proclamation, made on 11 November 1958 by the Governor, Dallas Brooks, was as follows:
An Australian stamp series of state floral emblems was issued in 1968. The pink heath was featured on the 13 cent stamp.<ref name=ANBG/><ref name=ANPSA2>Template:Cite web</ref> In 2014, a 70-cent stamp labelled as "Common Heath" was issued.<ref name=ANPSA2a>Template:Cite web</ref> The pink heath is also depicted on the Victorian driver's licence.<ref name=Silkstone>Template:Cite news</ref> In 1973, a depiction of pink heath was added to the armorial bearings for Victoria.<ref name=parliament>Template:Cite web</ref>
See also
[edit]Footnotes
[edit]References
[edit]External links
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