Awabuki Sweet Viburnum

Viburnum odoratissimum var. awabuki
Shrub
Opposite
Simple
White
Green

This shrub or small tree usually grows 1-4 m tall, but may occasionally reach up to 6 m in height at maturity. It develops brownish-grey bark on its older stems while its younger stems are green or reddish-tinged and hairless. It has become popular as a garden ornamental in recent years, with a cultivar known as ‘Emerald Lustre’ the most common in cultivation. It is different from typical Sweet Viburnum (Viburnum odoratissimum var. odoratissimum), which has been grown for many years in Australia and does not seem to be invasive.

Common names 
Also known as: Awabuki Sweet Viburnum,
Family 
Caprifoliaceae
Deciduous 
No
Flowering time 
Spring and Summer
Native/Exotic 
Exotic
Origin 
Taiwan and Japan
Notifiable 
No
State declaration 
Nil
Council declaration 
NIL - Reduce
Known distribution 

Awabuki Sweet Viburnum was first reported becoming a serious problem in the Coffs Harbour area on the northern coast of NSW in 2010, with control of this species being undertaken in several bushland sites (i.e. at Korora, Coffs Creek, Mullaway, Arrawarra, Sawtell and Toormina). It also been recorded as a weed in the Port Macquarie, Sunshine Coast and Brisbane (including Stretton Wetlands, Tall Trees Circuit Park, Karawatha Forest) in recent years. Most of the infestations of this species appearing in bushland currently consist of seedlings and juvenile plants, with relatively few mature plants established at this stage. 

Habitat 

Awabuki Sweet Viburnum is a potential weed of rainforest gaps and margins, riparian vegetation, disturbed bushland and forestry plantations in subtropical, tropical and warmer temperate regions.

Habit 

Its has a dense spreading habit, becoming more open, multibranched with a rounded canopy when mature. 

Impact and control methods 

Awabuki Sweet Viburnum has quickly spread from gardens into the understorey of rainforest, riparian and swamp forest communities in the Sunshine Coast, Brisbane, Port Macquarie and Coffs Harbour areas in recent years. As it is fast-growing and readily spread by animals that eat its fruit, it has the potential to become a serious environmental weed in these habitats.

Stem and leaves 

 The paired leaves are borne on green or reddish stalks 1-3 cm long and are hairless. These leaves are relatively large (10-20 cm long and 4-9 cm wide) with irregularly toothed to almost entire margins and usually have pointed tips. They are thick and leathery in texture, bright green in colour, with a glossy or lustrous appearance. However, young leaves and new growth is often slightly coppery tinged.

Flowers and fruits 

The small white flowers are produced in branched clusters (6-13 cm long) at the tips of the branches in spring. Large numbers of the sweet-smelling flowers (up to 7 mm across) are present in each cluster. Each flower has five tiny green sepals (2-4 mm long), five small white petals, and five cream or pale yellow stamens. The petals are fused together into a short tube (3-4 mm long) at the base and have spreading lobes with rounded tips. The small egg-shaped fruit (about 8 mm long and 5-6 mm wide) turn from green to red or blackish in colour as they mature. They are fleshy but contain single hard seed in the centre.

Reproduction and dispersal 

This species mainly reproduces by seed, which are thought to be dispersed by birds and other animals that eat the bright red mature fruit. Seeds may also be spread into bushland areas in dumped garden waste.

Similar species 

Awabuki Sweet Viburnum is very similar to Sweet Viburnum (Viburnum odoratissimum var. odoratissimum). However, Awabuki Sweet Viburnum has larger bright green leaves that are leathery and glossy in appearance, while Sweet Viburnum has smaller dull green leaves that are not thick and leathery.

Replacement species 
Sweet Viburnum (Viburnum odoratissimum var. odoratissimum)