Seed Notes 10
woody perennials. They
range from dwarf shrubs
suitable as groundcovers,
to medium shrubs reaching
several metres in height.
Their leaves, which are more
often than not opposite,
small and narrowly linear,
all exhibit the distinctive
aromatic smell of the family
Myrtaceae. Many species
within the Chamelaucium
alliance have attractive,
long lasting ornamental
flowers, in particular the
bells of the Darwinia and
the small waxy flowers of
the Chamelaucium. Many
species have great potential
for ornamental horticulture,
presenting an important
future for floriculture (e.g.
Flowers of the genus
yellow, pink and red while
those of the Chamelaucium
occur in a range of colours
from white to pink and to
red. Verticordia flowers
are feathery and often
borne singly but appearing
as heads or spikes. They are
generally brightly coloured,
ranging from yellow to red
and to purple. Inter-generic
hybridisation may occur
between different species
within the genera.
The three genera,
tribe Chamelaucieae belonging
to the Chamelaucium alliance
of the family Myrtaceae.
They share many distinctive
characteristics and will be
treated in this publication as a
group. The genus Darwinia was
named after Dr Erasmus Darwin,
the grandfather of the naturalist
Charles Darwin. The meaning of
the name Chamelaucium is not
very clear, although in Greek,
chamai means dwarf or on the
ground and leucos means white.
Roman goddess Venus due to
the beauty of the flowers.
Above: Verticordia aurea. Below: Verticordia fragrans. Photos – Anne Cochrane
This issue of
will cover the genus
No. 10 Darwinia, Chamelaucium and Verticordia
These three genera are
endemic to Australia, with a
large proportion of species
of Darwinia and Verticordia
found in south-western
Australia. Chamelaucium is
entirely endemic to Western
Australia. There are more
than 150 species in the genus
60 in Darwinia. All these plant
genera occupy a prominent place
in many shrub and heathland
communities together with other myrtaceous genera such
as Callistemon, Agonis, Leptospermum, Melaleuca and
drained soils, although many grow in a wide range of soils and
climatic conditions. Darwinia are found in sandy coastal heaths
and in the species rich mountains of the Stirling Range National
Park. Verticordia and Chamelaucium can be found on laterite,
granites and in deep siliceous sand. Many populations of these
genera are at risk of local extinction in the near future due to
a range of threatening processes. These include disease, weed
invasion, salinity, small population sizes, habitat fragmentation
and/or continued land clearing. Over-picking of flowers from
the wild also has impacted wild populations of several species,
common and rare. In addition, Darwinia are considered
susceptible to the dieback disease, Phytophthora cinnamomi.
Species in the Chamelaucium alliance have indehiscent fruits,
or nuts, that usually contain only one seed and are shed
annually. They are never discharged but the entire flower
dries and breaks off below the receptacle. Seed must be
collected when mature and timing of collections is important.
It is possible to collect seed of each of the three genera
from below plants but insect predation may be higher in
such collections. Old flowers of Verticordia form the fruit
and hence old faded flowers are collected when they easily
come off the plant. Both Darwinia and Chamelaucium form
fruits that appear different from the flowers and turn brown
and leathery to hard when ripe. For most species in the
three genera several months from the beginning of flower
initiation to seed collection are needed. Most Darwinia and
whereas Verticordia may be either spring or summer flowering
and seed is ripe for collecting mid summer.
Above: Darwinia citriodora.
Photo – Andrew Crawford
Approximate distribution of
Darwinia, Chamelaucium and
Most species in the Chamelaucium alliance are likely to be
pollinated by either specialised or unspecialised insects, and
may include native bees and wasps. Darwinia species that have
a conflorescence surrounded by bracts may possibly be bird-
pollinated whereas most other members of the genus are
thought to be insect-pollinated.
It has been postulated that
Verticordia grandis may be bird
pollinated due to the flower
structure. Apparent pollinator
mutualisms also have been reported
for some other species of Verticordia.
Profuse flowering in some species
indicates intense competition for
pollinators. Honey eating birds are
frequent visitors to the flowers of
all three genera.
Seed quality assessment
It is very difficult to determine from a cursory visual assessment
whether or not a seed has formed within the fruits of Darwinia,
in Verticordia. To determine whether seed has set, it is necessary
to perform a cut test on a representative sample of fruit. Simply
dissect the fruit with a scalpel blade. If you wish to keep the
seed for germinating then care is needed not to damage any
seed found. It is preferable to
use a microscope for this job.
Seed needs to be white, firm
and translucent for it to
be considered healthy
and potentially viable.
In Darwinia and Chamelaucium,
it is far easier to determine
whether seed has formed
within the fruit. The fruit
will be slightly swollen at the
base and in the case of the
latter, it may be glossy
and not shrivelled.
Darwinia collina seed dissected from fruit
Species in all three genera are
considered difficult to grow from
seed. Plants have traditionally
been propagated by cuttings.
It is likely that seed dormancy
in Verticordia, Darwinia and
Chamelaucium is influenced by
a complex interaction of factors.
The breakdown of seed dormancy
and the transition of dormant
seed to germinable seed appears
to require not only the removal
of the seed coat, which acts as
a barrier to water uptake, but
also the addition of growth
hormones to overcome an
It is possible that the
hypanthium (floral tube)
and perianth (sepals and
petals of a flower) might
help protect the seed
from weathering, thus
Dormancy breaks down
naturally over time because
of weathering and soil
disturbance. Many species in
these three genera appear
to have a strong reliance on
fire to stimulate germination,
indicating heat and/or smoke
may help alleviate dormancy
in seeds. Recent research
has demonstrated smoke
responsiveness for some
species. Naked seed from the
cut test mentioned under Seed
Quality Assessment can be grown
in the jelly-like substance agar, or
put into small dishes with filter
paper and kept moist. Some seed
will germinate after several weeks.
If access to the growth hormone
gibberellic acid is available then
additions of this to the agar or
filter paper at 25 mg per litre will
greatly assist germination.
aorocladus; central right fruit coloured
Darwinia chapmaniana seed
Darwinia leiostyla seed
Darwinia acerosa. Fruit on right
Darwinia oxylepis seed and fruit.
flower revealing seed.
Chamelaucium, Darwinia and
Photos – Anne Cochrane
to provide information
on seed identification,
collection, biology and
germination for a wide
range of seed types
for Western Australian
They have been written and
compiled by Anne Cochrane,
Manager of DEC's Threatened
Flora Seed Centre.
Concept by Grazyna
Designed by DEC’s
Graphic Design Section.
Seed Notes are
are published by
Wildflower Society of
Western Australia (Inc.)
with assistance from
the Western Australian
and the Department
of Environment and
Blake, T. L. 1981. A Guide to Darwinia and
Cochrane, A., Brown, K., Cunneen, S. and
Kelly, A. 2001. Intra- and inter-specific
variation in seed production and germination
in 22 rare and threatened Western Australian
taxa in the genus Verticordia (Myrtaceae).
Journal of the Royal Society of Western
Australia 84, 3.
Elliot, W. R. and Jones, D. L. 1984.
Sharr, F. A. 1978. Western Australian Plant
Names and their Meanings. A Glossary.
University of Western Australia Press, Perth.