M. FAGG 
Backhousia 
citriodora 
The genus Backhousia includes seven 
species, all of which are confined to the 
coastal rainforest areas of New South 
Wales and Queensland. Commonly 
referred to as ‘myrtles’ this group of plants, 
comprising trees and shrubs with strongly 
aromatic foliage, is included in the family 
Myrtaceae. 
B. citriodora occurs naturally in the 
Queensland coastal forests from Brisbane 
to Mackay and is known by several 
vernacular names including lemon iron- 
wood, lemon-scented myrtle and sweet 
verbena tree. It is a medium-sized shrub 
or tree, to 8 m tall with a low-branching 
habit. Often in cultivation small branches 
take root where they touch the ground. 
These branches are easily severed and 
replanted. 
The leaves of B. citriodora are a fresh 
green colour and strongly lemon-scented. 
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They are attractively veined and oval or 
lance-shaped in outline, 50-100 mm long 
with slightly toothed margins and a 
pointed apex. The young foliage is reddish 
and the young shoots and undersides of 
the leaves are often hairy. 
The very attractive white flowers are 
numerous and produced in long-stalked 
clusters. The outer part of an individual 
flower consists of a bell-shaped hairy 
receptacle with 5 persistent spreading 
calyx lobes. These are surmounted by 5 
small petals about 5 mm long and numer¬ 
ous fluffy stamens which are twice as long 
as the petals. 
The fruit is a nut-like capsule which 
contains several small seeds. These are 
occasionally released but are generally 
retained until the whole fruit falls from the 
tree. 
B. citriodora is slightly frost-tender 
when young but can be grown outside in 
frosty areas provided it is planted in a 
sheltered position in semi-shade. Several 
specimens are thriving in the Australian 
National Botanic Gardens in the Rainfor¬ 
est Gully where some protection is 
provided by the tree canopy and surround¬ 
ing shrubbery. Temperatures as low as 
-8°C have been recorded in this section 
of the Gardens during winter. 
The best method of propagation is from 
tip cuttings taken in March. Roots will 
develop much more effectively if the bases 
of the cuttings are dipped in a rooting 
hormone* consisting of 500 ppm IBA 
(indole butyric acid) and 500 ppm NAA 
(naphthaleneacetic acid). The soil for 
planting should be rich, moist, well 
mulched and well composted. 
B. citriodora has great potential for use 
in domestic gardens for its aesthetic value 
and fragrance. It is easily maintained and 
in addition can be used as a container 
plant for indoors. 
340 
* See Appendix 
