Their botany, essential oils and uses



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Synonym

Accepted name

Astroloma marginatum

Melaleuca marginata

Callistemon acuminatus

M. flammea

Callistemon brachyandrus

M. brachyandra

Callistemon brevisepalus

M. brevisepala

Callistemon buseanus

M. buseana

Callistemon chisholmii

M. chisholmii

Callistemon citrinus

M. citrina (Curtis) 

Dum.-Cours.

Callistemon comboynensis

M. comboynensis

Callistemon flavovirens

M. flavovirens

Callistemon formosus

M. formosa

Callistemon glaucus

M. glauca

Callistemon gnidioides

M. sphaerodendra

Callistemon hemistictus

M. hemisticta

Callistemon lanceolatus

M. citrina (Curtis) 

Dum.-Cours.

Callistemon lazaridis 

M. lazaridis 

Callistemon linearifolius

M. linearifolia

Callistemon linearis

M. linearis var. linearis

Callistemon macropunctatus M. rugulosa

Callistemon macropunctatus 

var. laevifolius

M. rugulosa

Callistemon megalongensis

M. megalongensis

Callistemon montanus

M. montana

Callistemon montis-zamia  M. montis-zamia 

Callistemon nervosus

M. nervosa

Callistemon pachyphyllus

M. pachyphylla

Callistemon pallidus

M. pallida

Callistemon paludosus

M. paludicola



Synonym

Accepted name

Callistemon pancheri

M. pancheri

Callistemon pauciflorus

M. faucicola

Callistemon pearsonii

M. pearsonii

Callistemon phratra

M. phratra

Callistemon phoeniceus

M. phoenicea

Callistemon pinifolius

M. linearis var. pinifolia

Callistemon pityoides

M. pityoides

Callistemon polandii

M. polandii

Callistemon pungens

M. williamsii subsp. 

williamsii

Callistemon pungens subsp. 

fletcheri

M. williamsii subsp. 

fletcheri

Callistemon pungens subsp. 

synoriensis

M. williamsii subsp. 

synoriensis

Callistemon pyramidalis

M. pyramidalis

Callistemon quercinus

M. quercina

Callistemon recurvus

M. recurva

Callistemon rigidus

M. linearis var. linearis

Callistemon rugulosus

M. rugulosa

Callistemon rugulosus var. 

flavovirens

M. flavovirens

Callistemon sabrina

M. sabrina

Callistemon salignus

M. salicina

Callistemon serpentinus

M. serpentina

Callistemon shiressii

M. shiressii

Callistemon sieberi

M. paludicola

Callistemon speciosus

M. glauca

Callistemon suberosum

M. dawsonii

Callistemon subulatus

M. subulata

Melaleuca synonyms


12

Melaleuc

a synon

yms


Synonym

Accepted name

Callistemon teretifolius

M. orophila

Callistemon viminalis

M. viminalis subsp. 

viminalis

Callistemon viminalis subsp. 

rhododendron

M. viminalis subsp. 

rhododendron

Callistemon viminalis var. 

minor


M. viminalis subsp. 

viminalis

Callistemon viridiflorus

M. virens

Callistemon wimmerensis

M. wimmerensis

Calothamnus suberosus

M. suberosa

Melaleuca acacioides subsp. 

alsophila

M. alsophila

Melaleuca acerosa

M. systena

Melaleuca apodocephala 

subsp. calcicola

M. calcicola

Melaleuca arenaria

M. tuberculata var. 

arenaria

Melaleuca calycina subsp. 

dempta

M. dempta



Melaleuca cardiophylla var. 

longistaminea

M. longistaminea

Melaleuca citrina Turcz.

M. lutea

Melaleuca coccinea subsp. 

eximia

M. eximia



Melaleuca coccinea subsp. 

penicula


M. penicula

Melaleuca coronicarpa

M. marginata

Melaleuca crosslandiana

M. nervosa

Melaleuca cymbifolia

M. halmaturorum

Melaleuca densa var. pritzelii M. pritzelii

Melaleuca halmaturorum 

subsp. cymbifolia

M. halmaturorum

Melaleuca lanceolata subsp. 

occidentalis

M. lanceolata

Melaleuca lanceolata subsp. 

planifolia

M. lanceolata

Melaleuca lanceolata subsp. 

thaeroides

M. lanceolata

Melaleuca lateriflora subsp. 

acutifolia

M. acutifolia

Melaleuca lateriflora var. 

acutifolia

M. acutifolia



Synonym

Accepted name

Melaleuca longistaminea 

subsp. spectabilis

M. spectabilis

Melaleuca maidenii

M. quinquenervia

Melaleuca minutifolia subsp. 

monantha


M. monantha

Melaleuca nervosa f. latifolia M. nervosa

Melaleuca nervosa subsp. 

crosslandiana

M. nervosa

Melaleuca paludosa 

M. glauca

Melaleuca smithii

M. quinquenervia

Melaleuca styphelioides var. 

squamophloia

M. squamophloia

Melaleuca tamariscina 

subsp. irbyana

M. irbyana

Melaleuca tamariscina 

subsp. pallescens

M. pallescens

Melaleuca urceolaris var. 

virgata


M. dichroma

Melaleuca virgata

M. dichroma

Melaleuca viridiflora var. 

angustifolia

M. quinquenervia

Melaleuca viridiflora var. β 

rubriflora

M. quinquenervia

Metrosideros citrina

M. citrina (Curtis) 

Dum.-Cours.

Metrosideros decora

M. decora

Metrosideros glauca

M. glauca

Metrosideros linearifolia

M. linearifolia

Metrosideros nodosa

M. nodosa

Metrosideros pinifolia

M. linearis var. pinifolia

Metrosideros quinquenervia M. quinquenervia

Metrosideros rugulosa

M. rugulosa

Metrosideros saligna

M. salicina

Metrosideros viminalis

M. viminalis subsp. 

viminalis

Metrosideros viridiflora

M. virens

Myrtus leucadendra

M. leucadendra

Petraeomyrtus punicea

M. punicea

Regelia punicea

M. punicea



13

Melaleuca is the basis of several industries in Australia and elsewhere. Predominantly 

these industries are based on the extraction of essential oils from the foliage of three 

species, Melaleuca alternifolia (but sometimes including minor use of M. linariifolia 

and M. dissitiflora), M. cajuputi subsp. cajuputi and M. quinquenervia. An emerg-

ing industry is underway in South-East Asia, especially on potentially acid-sulfate 

soils, where trees are being grown primarily for roundwood, and research is being 

undertaken into the suitability of their wood for fibre. In view of the challenge to find 

novel sources of commercially significant oils, we have been collecting samples over 

the past three decades, and have been extracting and analysing the oils. In spite of this 

activity, when this book was mooted, information on the oils of about 100 species was 

still lacking. Dedicated fieldwork was undertaken in south-western Western Australia, 

where most of the unsampled species occurred, and requests were made of individuals 

and organisations that might have been in a position to assist. These efforts were suc-

cessful and there are only one species and four infraspecific taxa for which there are 

still no data on their essential oils. The majority of the oils reported in this volume have 

not previously been described in the scientific literature. As a result of the fieldwork, 

several species (e.g. M. halophila, M. hamata, M. ochroma) have been identified as 

potentially valuable sources of essential oils and may warrant further investigation of 

their oil content and yield.

As it is presently circumscribed, Melaleuca consists of 

290 species with 37 infraspecific taxa. Work on the sys-

tematics of the genus in recent years has indicated that 

Melaleuca may be made larger due to the inclusion of 

several genera presently regarded as distinct. As this work 

is at present incomplete, Melaleuca is treated in a conven-

tional concept in this volume, although with the addition 

of the species previously known as Callistemon. Many of 

the species included in this volume have previously been 

treated only skeletally and, for these, detailed descriptions 

are being published for the first time. Distribution maps 

are included for all species, and colour photographs of the 

flowers are included for those we have been able to source.

Apart from essential oils, melaleucas have been used 

for a wide range of purposes, from making brushwood 

fencing, as ornamental shrubs, as shelterbelt species for 

farmland, for rehabilitating salt-affected lands, for street 

and park trees, and so on. One interesting potential use 

for M. bracteata is as a source of water-soluble betaines—

compounds that act as osmoprotectants against stress in 

plants. These compounds may increase stress tolerance in 

agricultural crops which in turn would increase national 

income from agriculture.

A threat to the future health and genetic diversity of a 

substantial number of Melaleuca species in eastern Aus-

tralia is from Puccinia psidii sensu lato (synonym Uredo 

rangelii). This exotic pathogen has the common name of 

myrtle rust in Australia but it is known as guava or euca-

lyptus rust elsewhere, with origins in Brazil. Myrtle rust 

targets species of the family Myrtaceae, including Mela-

leuca. First observed in Australia on the central coast of 

New South Wales in 2010, it has now spread from Victoria 

Preface


14

Pre


fa

ce

to northern Queensland. In susceptible plants, young 



spore-covered leaves and shoots become curled and dis-

torted and severe infection can cause shoots to die, causing 

these plants to become stunted after repeated infections. 

In the worst cases, death of the whole plant can occur after 

repeated destruction of new growth. As this book goes to 

press, this disease is of concern to all with an interest in 

the conservation and sustainable use of Australian plants 

of the family Myrtaceae.



Joe Brophy, Lyn Craven, John Doran

September 2013



15

Historical context

Melaleuca is almost entirely Australian in its distribution yet the first of its species to 

be formally described, Melaleuca leucadendra, was based on material from Ambon, in 

present-day Indonesia. Georgius Everhardus Rumphius, a merchant with the Dutch 

East Indies Company, compiled a detailed account of many of the plants growing in 

the Malesian biogeographical region but this was not published until 1741; this impor-

tant work has recently been translated into English and published with annotations 

(Rumphius 2011). The plant we now know as Melaleuca leucadendra was called Arbor 

alba by Rumphius. Rumphius’ 1741 publication predated the accepted starting point for 

the scientific botanical nomenclature of flowering plants and the formal description of 

the species occurred in 1754 when the Swedish botanist Carolus Linnaeus gave it the 

name Myrtus leucadendra, taking his descriptive data from Rumphius’ work (Linnaeus 

1754). Subsequently, Linnaeus realised that his Myrtus leucadendra did not have very 

much in common with the other species of Myrtus and in 1767 he described the genus 

Melaleuca to accommodate this plant (Linnaeus 1767).

The nomenclature applied to the first endemic Australian 

melaleucas to be described was inconsistent due to a lack 

of appreciation of the relationships of the species. Doubt-

less this was due to the limited numbers of specimens that 

had been collected and consequent uncertainty as to how 

the genera of Myrtaceae should be circumscribed. Several 

species, such as M. armillaris and M. decora, described in 

1788 and 1796, respectively, initially were placed in Metro-

sideros. In other cases, the author recognised a relationship 

with Linnaeus’ Melaleuca and the species was placed in 

that genus, e.g. M. ericifolia and M. gibbosa, described 

in 1797 and 1806, respectively. From the perspective of 

having a foundation on which to build new knowledge 

of Melaleuca species, George Bentham’s treatment of the 

genus in his Australian flora (Bentham 1867) provided the 

first comprehensive summary of the species known, and 

those species that had been described in Metrosideros were 

then brought into Melaleuca. Bentham’s important account 

enabled later workers to identify their materials and thus 

determine if there were additional species that should be 

described. During the next 100 years, many species were 

added to the genus, including two from New Caledonia 

(M. brongniartii and M. gnidioides) and one from Lord 

Howe Island (M. howeana).

Melaleuca was circumscribed by Bentham (1867) in part 

as having stamens united in bundles opposite the petals. 

 

Taxonomic history



 

and systematics



1. T

ax

onomic history and sy



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16

The related genus Callistemon was distinguished from 



Melaleuca by Bentham as having free stamens, although 

he noted that the stamens of Callistemon speciosus (now 

M. glauca) were often in bundles. Most of the species 

placed in Callistemon are Australian but five species were 

also described from New Caledonia, two of which have 

stamens in bundles; one wonders why these were not there-

fore placed in Melaleuca. The recognition of Melaleuca and 

Callistemon as separate genera had been regarded as being 

artificial from the time of the description of the latter. 

When describing Callistemon, Robert Brown (1814, p. 547) 

wrote: ‘The maximum of Melaleuca exists in the principal 

parallel, but it declines less towards the south than within 

the tropic, where its species are chiefly of that section 

which gradually passes into Callistemon, a genus formed of 

those species of Metrosideros that have inflorescences simi-

lar to that of Melaleuca, and distinct elongated filaments’. 

Ferdinand Mueller, who was well acquainted with both 

genera in the field and in the herbarium, also regarded Cal-

listemon as being artificial (Mueller 1864). Bentham may 

in fact have had his own doubts about the distinctness of 

Callistemon, for he commented in Flora Australiensis that 

Callistemon ‘passes gradually into Melaleuca, with which 

F. Mueller proposes to reunite it’ (Bentham 1867, p. 118). 

The majority of authors have accepted the two genera as 

being distinct but the nineteenth century botanist Henri 

Ernest Baillon included Callistemon and two other genera 

(Conothamnus and Lamarchea) in Melaleuca, recognis-

ing them at sectional level (Baillon 1876). In 1998, Lyn 

Craven and John Dawson transferred the New Caledonian 

Callistemon species to Melaleuca, as they considered the 

endemic New Caledonian species of the complex should be 

placed in the same genus (Craven and Dawson 1998). Cra-

ven (2006) then discussed morphological evidence relevant 

to the separation of the two genera and transferred all the 

accepted Australian species of Callistemon to Melaleuca.

Studies based on 

morphological evidence

Surprisingly for a genus of nearly 300 species, few revi-

sionary-level treatments of species groups or of prescribed 

geographical regions within Australian Melaleuca have 

been published. Perhaps fittingly, in view of the ecologi-

cal and/or economic significance of its several species, the 

first was an account of the broad-leaved paperbarks, the 

M. leucadendra species group, by Stan Blake (Blake 1968); 

these species are a common component of savannah and 

woodland communities in northern and north-eastern 

Australia, south-eastern Malesia and New Caledonia. 

John Carrick and Kosmyn Chorney (Czornij) published a 

revisionary-level account of the South Australian species 

of Melaleuca in 1979 which gave an insight into arid-zone 

species of the genus (Carrick and Chorney 1979). Norm 

Byrnes in 1984 published the first part of a concise revision 

of the Melaleuca species of northern and eastern Australia 

(Byrnes 1984, 1985, 1986). Several of these species were 

removed from Melaleuca in 1989 as a result of the resurrec-

tion of Asteromyrtus (Craven 1989). Asteromyrtus is related 

to Agonis and Leptospermum and presumably had been 

included in Melaleuca only because its stamens are in bun-

dles. Byrnes’ M. punicea was also removed from the genus 

because of its anomalous androecium, gynoecium and seed. 

Initially the species was placed in Regelia (Barlow 1987a) 

but it was subsequently placed in the new genus Petraeo-

myrtus (Craven 1999), as the species was as anomalous in 

Regelia as it had been in Melaleuca. However, following 

recent investigations using molecular data, M. punicea is 

treated in the present volume under Melaleuca (see below).

Bryan Barlow initiated revisionary studies of Melaleuca 

in Canberra in the early 1980s. In 1986, Barlow published 

the results of his studies of three species complexes: the 

M. acacioides, M. tamariscina and M. minutifolia com-

plexes (Barlow 1987b). Subsequently, the M. cuticularis 

and M. lanceolata species groups were revised by Barlow 

and Kirsten Cowley (Barlow and Cowley 1988) and the 

M. fulgens and M. laxiflora species groups were revised 

by Cowley and collaborators (Cowley et al. 1990). An 

enumeration of the Australian species of Melaleuca sensu 

stricto was published by Craven and Brendan Lepschi in 

1999; this paper included an identification key—the first 

key including all these species of the genus since 1867 

(Craven and Lepschi 1999). Four species belonging to 

the M. thymoides species group—M. lutea, M. pungens, 

M. striata and M. thymoides—were not included in the 

1999 enumeration, as Craven, at that time, considered the 

species of this group warranted separate generic status; 

however, in the present volume they are again included 

as melaleucas.

Incorporating DNA 

evidence in classification

Plant classification until recently has been based largely 

upon morphological evidence, utilising data from anatomy, 

cytology, chemistry (secondary metabolites) and any other 

sources where these have been available. The overarch-

ing objective of classification has been to group plants 

according to their presumed natural relationships, with 

putatively closely related species classified together. The 

technological advances that have permitted sequencing 

of DNA (deoxyribonucleic acid), together with develop-

ment of computer programs for detecting related species, 

have enabled biologists to study the genetic relationships 


17

1. T


ax

onomic history and sy

stematics

of plants in detail for the first time. The consequences of 

such studies for taxon delimitation, and thus classification, 

are varied. In some cases, generic circumscriptions are sup-

ported by analysis of DNA data and there are no changes 

to the classification, and hence nomenclature, of a genus. 

In other cases, the current classification is not supported, 

with part or all of the species sampled falling (or ‘nesting’) 

within one or more other genera. There is no automatic 

procedure to be adopted in such cases. Typically, if all the 

species of a genus or group of genera nest within a single 

genus, a decision has to be made to either combine all the 

genera into one or to break the original single genus into 

several. This clearly has implications for nomenclature. In 

other cases, some of the species of a genus are found to nest 

within another, with the remaining species still comprising 

a distinct group, and in those cases the nested species are 

transferred to the other genus. This still has implications 

for nomenclature, especially if the name of the genus is 

transferred along with the nested genus, as the remaining 

species will then require a new generic name.

Species of Melaleuca and the morphologically closely 

related genera Beaufortia, Calothamnus, Conothamnus, 

Eremaea, Lamarchea, Phymatocarpus and Regelia, and 

including M. punicea (Petraeomyrtus), the four species of 

the M. thymoides group, and several Australian and New 

Caledonian species of Melaleuca that formerly had been 

placed in Callistemon, were included by Robert Edwards 

and his collaborators in an analysis of chloroplast DNA 

data (Edwards et al. 2010). Chloroplast DNA is maternally 

inherited, and phylogenies derived from chloroplast DNA 

data give a good estimate of the maternal ‘family tree’. 

The results of Edwards et al. (2010) showed there were 

three major groupings or clades, each of which contained 

species of Melaleuca sensu stricto. The whole Melaleuca 

group itself formed a well-supported clade relative to the 

outgroup taxa included in the analyses. In one of the three 

clades are species of the M. leucadendra, M. acacioides, 

M. scabra and M. thymoides groups, two New Caledonian 

species previously placed in Callistemon, M. punicea, 

and representative species of Beaufortia, Calothamnus, 

Conothamnus,  Eremaea,  Lamarchea,  Phymatocarpus 

and Regelia. In a second clade are representatives of the 

M. cuticularis, M. fulgens and M. laxiflora groups, together 

with Australian species previously placed in Callistemon 

and several species not placed within a particular group-

ing. The third clade contains members of the M. bracteata, 

M. cuticularis, M. lanceolata and M. minutifolia groups, 

together with other species not allocated to a particular 

grouping and the morphologically anomalous M. foliolosa.

The incorporation of nuclear DNA data in phylogenetic 

studies enables the paternal contribution to be assessed; 

using only the maternal chloroplast data could give a 

biased result. The broad structure of the inferred chloro-

plast DNA phylogeny given in Edwards et al. (2010) is in 

agreement with the nuclear DNA phylogenies of Ladiges et 

al. (1999) and Brown et al. (2001); these were based upon 

data derived from a smaller number of species than in the 

study of Edwards et al. (2010) but the sampling was drawn 

from most of the various genera of the complex.

Current and future 

classification challenges

The taxonomic implications of the DNA studies are that 

one either includes all the related genera within Melaleuca 

or one retains the existing segregate genera and recognises 

many new ones, perhaps 10 or more. Given the lack of 

distinctive morphological features available to differenti-

ate many of them, such new genera would not be readily 

recognisable. Consequently, Melaleuca will be enlarged to 

include Beaufortia, Calothamnus, Conothamnus, Eremaea, 

Lamarchea, Phymatocarpus and Regelia (L.A. Craven, R.D. 

Edwards and K.J. Cowley, in preparation). The species 

treated in the present volume are those that accord with 

the conventional concept of Melaleuca and also include 

M. punicea, the M. thymoides group and those species 

previously placed in Callistemon.

Morphological evidence also has been a primary source 

of data for developing species’ concepts in Melaleuca. It 

is unlikely that this situation will change dramatically in 

the foreseeable future but the few studies that have been 

made using DNA data have shown that this will be a very 

powerful tool for taxonomists. Linda Broadhurst et al. 

(2004), utilising nuclear restriction fragment length poly-

morphism (RFLP) data derived from a range of Western 

Australian populations of the broombush (M. uncinata) 

complex (and including one South Australian popula-

tion from the type locality of M. uncinata), found that 

phylo genetic analysis showed the sampled populations 

represented seven species of the broombush complex. The 

results of the phylogenetic analysis were congruent with 

those of a parallel morphological study that encompassed 

the whole of the broombush complex in Western Australia 

(Craven et al. 2004).

The broad-leaved paperbark group (M. leucadendra 

group) is an ecologically important component of vegeta-

tion in northern and eastern Australia. Conventionally it 

has been regarded as a taxonomically difficult group and, 

in the mid nineteenth century, it was treated by Bentham 

(1867) as a single species with numerous varieties. Blake, 

with an insight gained from studying the complex in the 

field, published a detailed and workable account of the 

group that, despite several new species being described 

since, remains the most useful guide to the group (Blake 

1968). One of the broad-leaved paperbarks, M. quinquen-

ervia, is a common wetlands tree in eastern Australia and 


1. T

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onomic history and sy



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18

also occurs naturally in Papua province of Indonesia, 



Papua New Guinea and New Caledonia, and is a major 

woody weed in Florida, United States of America (USA). 

This species is harvested for its essential oil, niaouli oil, in 

New Caledonia and also in Madagascar, where it is cul-

tivated for this purpose. In a study using DNA sequence 

data from two chloroplast and two nuclear regions, Cook 

et al. (2008) found that the genome of M. quinquenervia 

contained alleles that link the species to several other 

broad-leaved paperbark species and that there was regional 

sharing of chloroplast haplotypes, indicating introgression 

or lineage sorting. This has significance for biological con-

trol studies of M. quinquenervia as it will be necessary to 

match the genetics of the weed populations with naturally 

occurring populations in Australia when seeking control 

agents. A significant conclusion of the Cook et al. (2008) 

study was that species boundaries within the complex were 

not clear. This work is being extended by Robert Edwards, 

drawing upon a comprehensive sampling of the complex 

across northern Australia and the results should be of 

interest to systematists and others.

The extent to which hybridisation has played a role 

in the evolution of Melaleuca species is not known but 

it may be important and occurs quite widely across the 

genus (Craven 2006). DNA studies may assist in clarifying 

species circumscriptions in the bottlebrush (Callistemon) 

group, which is at least as difficult taxonomically as the 

broad-leaved paperbarks. The bottlebrush M. paludicola 

and its putative close relatives M. phratra, M. quercina, 

M. sabrina and M. wimmerensis make up one group 

worthy of investigation. The red-flowered Queensland 

bottlebrushes M. hemisticta, M. lazaridis, M. montis-zamia 

and M. pyramidalis are another, as there are populations 

in southern Queensland that presently are not definitively 

identifiable to one of these species and the whole complex 

requires a comprehensive population genetics study of the 

type conducted by Broadhurst et al. (2004) on members of 

the broombush group. Similarly, the relationship between 

M. citrina and M. subulata in southern New South Wales 

and eastern Victoria needs investigation. Bill Molyneux 

has described Callistemon forresterae, C. genofluvialis, 

C. kenmorisonii and C. nyallingensis from this region 

(Molyneux 1993, 1994, 1997, 2005) but these are regarded 

by one of us (LAC) as being hybrids or hybrid derivatives 

between M. citrina and M. subulata and are not accepted 

as species in the conventional sense; consequently, they 

are not included in the present volume. Apomixis in two 

bottlebrush species was studied by James (1958) and this 

genetic process may also be a factor in the evolution and 

relationships of the bottlebrushes in eastern Australia 

(Craven 2009).

It is clear there is need for an infrageneric classification 

of Melaleuca, with closely related species being grouped 

together in sections and subsections etc. Already there are 

nearly 300 species in the genus and with the transfer of the 

species flagged above there will be nearly 400; this is too 

large a number to be left in an unstructured arrangement. 

A preferred classification would be one based upon mor-

phological data alone, but in the case of Melaleuca these are 

not sufficient and it will be necessary to incorporate DNA 

results in the synthesis. The DNA studies that have been 

published to date, while sufficient to support the merger 

of the genera of tribe Melaleuceae into a single genus, i.e. 

Melaleuca, do not adequately resolve the clades that were 

found and contain too few species to permit a classifica-

tion to be prepared. Research presently underway at the 

Australian National University, Canberra, using next-

generation sequencing methods and a very much greater 

sampling of species across Melaleuca sensu lato should give 

information that will guide development of a robust clas-

sification (Mike Crisp and Bo Choi, pers. comm.).



19

General information

Family and tribe

The genus Melaleuca is in the family Myrtaceae and tribe Melaleuceae.

Botanical name

The generic name is derived from the Greek melas, meaning black or dark, and leucon, 

meaning white—apparently alluding to the white branches and black trunk of the first 

named species, M. leucadendra, the trunks of which are often blackened by fire.

Common names

Species with thick, spongy, peeling bark comprising many papery layers are commonly 

referred to as ‘paperbarks’, with some qualifying adjective (e.g. silver-leaved paperbark, 

M. argentea). In southern Australia, the common name ‘honey myrtle’ is also well 

established for many shrub-sized species (e.g. bracelet honey myrtle, M. armillaris). A 

few have distinctive Aboriginal (e.g. winti, M. arcana) or locality (e.g. South Australian 

swamp paperbark, M. halmaturorum) names, while some are referred to as ‘tea tree’ 

(e.g. black tea tree, M. bracteata), a common name shared with many species of Lepto-

spermum. As explained above, this treatment of Melaleuca includes species previously 

belonging to the genus Callistemon. They retain their common name of ‘bottlebrush’ 

which alludes to the resemblance of the flowers and emerging new growth to a kitchen 

bottlebrush (e.g. crimson bottlebrush, M. citrina).

Ploidy

The great majority of Melaleuca species are diploid with 



2n = 22 (Brighton and Ferguson 1976; Rye 1979). Poly-

ploidy appears to be relatively infrequent in this genus, 

with only a few recorded instances of aneuploidy 

(2n + 2 = 24), triploidy (3n = 33), tetraploidy (4n = 44) 

and hexaploidy (6n = 66) (James 1958; Brighton and 

Ferguson 1976; Rye 1979) which have been linked with 

hybridisation and apomixis. The apomictic species, M. lin-

earis, may have populations that are diploid, triploid or 

tetraploid (James 1958).

Introduction to

 

the genus Melaleuca



20

2. I


ntr

oduction to the genus 



Melaleuc

a

Number of species

Melaleuca, as circumscribed in this work, comprises 290 

species (327 entities inclusive of infraspecific taxa). As 

such, it is the third-largest genus of Myrtaceae after Euca-

lyptus and Syzygium in the Australasian region.

Botanical features

Habit and size

Melaleucas range from woody, multistemmed shrubs to 

very large, single-stemmed trees of timber-producing 

value. By far the majority of species are shrubs or small 

trees less than 10 m tall, 40 of which do not exceed 1 m in 

height. These ground-hugging types are found largely in 

the south of Western Australia. Fifteen species have been 

documented as being over 10 m in height, with seven of 

these species exceeding 20 m. Boland et al. (2006) report 

that M. cajuputi has been recorded with heights up to 

46 m in the Northern Territory and is the tallest tree in 

the region; similarly, M. leucadendra has been measured 

to 43 m in northern Queensland (Figure 1).

Bark

The bark of the majority of species is of the papery type. 



Here, the bark consists of thin, paper-like layers of cork 

separated by thin fibrous layers, which may reach 5 cm in 

thickness. The outer layers peel naturally to give a distinc-

tive ragged, torn and unkempt appearance to the lower bole 

(Figure 2A). In addition, a substantial proportion (c. 20%) 

of Melaleuca species has hard, deeply furrowed, rough bark, 

as exemplified by M. bracteata (Figure 2B). There is a fur-

ther 20% of species where the bark is described as fibrous. 

There is some overlap in bark types in some species. For 

example, M. clarksonii is variously described as displaying 

all three bark types in different individuals.

Foliage


Melaleucas are evergreen and usually carry abundant 

green, bluish-green, grey-green or silvery-grey foliage 

unless drought or other stresses (e.g. salt) have stimulated 

leaf abscission. Leaves are minute to large. In all, 60% of 

recognised species have short (<30 mm long) to very short 

(<10 mm) leaves, while the others have medium to long 

leaves. Melaleuca leucadendra, with its narrow lanceolate 



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