TAXONOMY
Division Angiosperm
Subclass Dicotyledonae
Family SAPINDACEAE
Previous Taxonomic Names
Linnaeus identified it as Ptelea viscosa in 1753 (CHAH, 2006). It was named Dodonaea viscosa by Phillip Miller in 1754 (Closs & West, 1993). Dodonaea was revised in 1984 by J.
G. West.
Taxonomic Identification Number 18354 (ANH et al 2005)
Taxonomic Status
Long lived woody perennial.
Common Names
Sticky Hop-bush, Giant Hop-bush, Broad leaf Hopbush, Candlewood, Narrow leaf Hopbush, Native Hop, Native Hop Bush, Soapwood, Switchsorrel, Wedge leaf Hopbush (ANBG n.d.)
MORPHOLOGY
Dodonaea viscosa
Spreading or erect shrub or tree up to about 5 m. Branchlets angled to flattened, usually slightly ribbed, smooth to covered with minute soft hairs. Leaves simple, stalkless or petiolate, linear to spoon-shaped, rarely wedged shaped, 1-15.5 cm long, 1-25 mm wide. Flowers in terminal panicles, 3-4 sepals, lanceolate to ovate. Capsule 3-4 winged and oval (Walsh & Entwisle 1996).
There are four subspecies of Dodonaea viscosa in Victoria which intergrade where populations overlap (Walsh & Entwisle 1996).
SUBSPECIES
• Dodonaea viscosa ssp. angustifolia – occurs in East Gippsland, NSW and Queensland. Does not occur naturally in the Corangamite region.
• Dodonaea viscosa ssp. angustissima (Slender Hop-bush)
Erect shrub to 4 m. Leaves stalkless, linear to narrowly oblong, sometimes oblanceolate, 3 - 9.5 cm long, 1-6 mm wide, irregularly wavy to irregularly and minutely toothed. Lateral venation conspicuous.
Intergrades with ssp. angustissima and spatulata. Mostly northern Victoria, NSW, QLD, ACT, NT, WA and SA. Does not occur in the Corangamite region.
• Dodonaea viscosa ssp. cuneata (Wedge-leaf Hop-bush)
Compact spreading shrub to 3 m. Leaves stakless or shortly petiolate, wedge- shaped to angular-obovate to narrowly obovate, 0.8—3.8 cm long, 4-9 (but less than 12) mm wide, truncate or obtuse, usually pointed, sometimes irregularly 2-3 toothed, lateral venation obscure, petiole, when present about 1 mm long.
Intergrades with ssp. spatulata. Mostly north-west Victoria, SA, QLD and NSW but also occurs naturally in the Corangamite region.
• Dodonaea viscosa ssp. spatulata (Sticky Hop-bush) Erect to spreading shrub to 4 m.
Leaves stalkless or petiolate, usually obovate, sometimes spatulate, rarely elliptic, 2.3-7.5 (but less than 9) cm long and 6-10 (but less than 18 )mm wide. Leaves broadly acute to o btuse, sometimes rounded, shortly pointy, entire or irregularly wavy or irregularly and minutely dentate. Lateral venation usually conspicuous on lower surface, petiole when present 1-10 mm long. The most variable of the species, especially in leaf morphology. Populations in the Grampians and surrounding ranges, and at Warrandyte, have been identified as known variants within this subspecies. Intergrades with ssp. cuneata and angustissima (Walsh & Entwisle 1996). Flora Information System records it around coastal Geelong.
HYBRIDS
Known to hybridise with D. boroniifolia in regions of overlapping distribution .D. viscosa ssp. cuneata known to hybridise with D. procumbens in the Grampians region. (Walsh & Entwisle 1996)
SIMILAR SPECIES
D. boroniifolila is a similar shrub but has feathery leaves (GAV n.d.).
A nursery cultivar of D. viscosa ‘Purpurea’ from New Zealand is a known garden escape. It is distinguished by its large leaves (to 12 cm long and 2.5 cm wide) and purple under-surface (Walsh & Entwisle 1996).
GEOGRAPHIC RANGE
Occurs in all regions of Victoria and across all mainland Australian states, the Pacific Islands, Asia, Africa and the Americas.
In Victoria the various subspecies occur in a variety of habitats.
• D. viscosa ssp. angustifolia – occurs in East Gippsland, NSW and Queensland. Does not occur naturally in the Corangamite region..
• D. viscosa ssp. angustissima – common in the north-west of the state, but also found across northern Victoria to East Gippsland. Also found in NSW, QLD, ACT, NT, WA and SA. Does not occur in the Corangamite region.
• D. viscosa ssp. cuneata – occurs mainly in the north-west of Victoria in open woodland and mallee scrub, but also in central highland open forests in high rainfall areas.
• D. viscosa ssp. spatulata – occurs mainly in southern Victoria in high rainfall areas. (Walsh & Entwistle 1996).
BIOREGIONS
Dodonaea viscosa ssp. cuneata occurs in the Central Victorian Uplands and Victorian Volcanic Plains in the northern and eastern parts of the Corangamite region.
PLANT COMMUNITIES
D. viscosa ssp. cuneata is typically found in dry forest communities, grasslands and grassy woodlands and some riparian ecosystems. Examples can still be found in the upper parts of the Moorabool, Leigh and Woady systems of the Corangamite region.
FRAGMENTATION
Unknown
POPULATION DENSITY
Unknown
RELEVANT HISTORY & RESEARCH
There has been trials into establishment and germination (see Semple and Koen, 1996).
BREEDING SYSTEMS FLOWERING
Inconspicuous, red, unisexual flowers in clusters during spring and summer (Gray & Knight 2001; Walsh & Entwisle 1996). Fertile flowers can be hermaphrodite (and functionally male or female or both) or unisexual (MacFarlane et al, 2000). The flowers usually have a short flowering period (Closs & West, 1993).
POLLEN
Pollen is dispersed by wind.
POLLINATION
Outcrossing via wind but the flower structure also suggests it is self-compatible.
POLLINATORS
Insects (Earl et al 2001).
The flowers have no attractant for pollinators. and the absence of petals allows the pollen to be dispersed unhindered by the wind. No nectar is produced, which in other plants is an attraction to pollinators (Closs & West, 1993).
SEED
SEED DESCRIPTION
Seed is enclosed in a three or four winged capsule that turns from red to tan-brown and becomes brittle as seed ripens. Each capsule contains 2-3 seeds that are black, 2-3 mm in length, and firm when ripe (Bonney 2003; Ralph 1994; Walsh & Entwisle 1996).
Information relating to seed weight and viability is somewhat conflicting: 170 seeds/gram (GAV n.d.)
Approximately 212 viable seeds/gram (Earl et al 2001). 79-132 germinants/gram (GAV n.d.).
Dodonaea viscosa ssp. angustissima – 56 germinants/gram after hot water treatment at 20-30°C with 12 hours of light. Data from a study which used only one batch of seed which had been bought three years prior to the study (Semple 1996).
SEED CROP
Collect seed from October to January. Monitor closely as seed is released immediately or within 3-14 days of maturity (Ralph 1994). Large quantities of seed can be easily collected (Earl et al 2001).
SEED DISPERSAL
Birds (Bonney 2003)
EXTRACTION & STORAGE
Dry after collection. Some capsules may need to be rubbed against wire screens to extract all seed (Bonney 2003; Ralph 1994). Seed retains viability for many years (Ralph 2003).
TREATMENT OPTIONS
To help shorten germination time, seeds can be dunked in very hot water for 30 seconds then cooled down rapidly. Untreated seeds will germinate well (Bonney 2003; Ralph 1994).
Nicking the seed coat will also hasten germination (Ralph 2003).
Ralph (2003) reported that D. subglandulifera achieved very good germination results if seed is stored dry for six weeks after treatment, then sown and noted that other Dodonaea species may also respond to this treatment.
Dodonaea viscosa ssp. angustissima – Three germination treatments were trialled by Semple & Koen (1996). This included a) no treatment, b) hot water treatment, and c) no treatment with no exposure to light. The hot water treatment proved by far the most successful.
PROPAGATION
Propagate from seed or cuttings (Earl et al 2001). Sow in late winter or spring (Bonney 2003).
GERMINATION TIME
Usually 2-4 weeks (Ralph 2003; Semple & Koen 1996).
FIELD ESTABLISHMENT
Well suited to direct seeding (Bonney 2003; Ralph 1994).
Will germinate readily if sown through a tyne to near 4 mm depth in lightly tilled soils (Bonney 2003). Natural regeneration from seed, stem and coppice, particularly after fire (Earl et al 2001).
Dodonaea viscosa ssp. angustissima – Semple and Koen (1996) found that direct drilling seed into a scalped seedbed consistently produced the highest number of emergents and seedlings at 12 months. Very few emergents resulted from surface sown seed, and it is hypothesized that burial is required to break seed dormancy.
SEED COLLECTION RANGE - Dodonaea viscosa ssp cuneata
Dodonaea viscosa ssp spatulata
Narrow collection range—within which, seed should be collected from remnant stands that are close to the revegetation project
There are two subspecies of Dodonaea viscosa that have been identified in the region. There are also records of Dodonaea viscosa that have not been clearly defined. Added to this, the nursery cultivar D. viscosa Purpurea is known near the coast but may also occur in other areas. It should not be used for seed collection for indigenous revegetation projects.
The distribution of Dodonaea viscosa ssp cuneata and Dodonaea ssp spatulata indicate a narrow collection range for each subspecies.
Consideration should be given to:
• Correct identification of subspecies and the introduced nursery cultivar
• Collect each subspecies separately and do not mix seed together
• Collect seed from healthy, large populations of an individual subspecies
• Separate individual populations. As seed can be stored for many years, small collections can be made over a number of years to build up stores of genetic material. Collect from as many plants as possible in a given population.
REFERENCES
ANBG n.d., Australian plant common name database, Australian National Botanic Gardens, Dept. of the Environment & Heritage, retrieved 18 Apr 2006,
<http://www.anbg.gov.au/common.names/>
ANH, ANGB & ABRS 2005, Australian plant name index, Australian National Herbarium, Australian National Botanic Gardens, Australian Biological Research Study, retrieved 18 Apr 2006,
<http://www.anbg.gov.au/cpbr/databases/apni.html> CHAH (2006) Census of Australian Plants
Close, J & West, Dr J (1993) Dodonaea—The Hop Bush (Australian Plants online http://farrer.csu.edu. au/ASGAP/APOL27/sep02-1.html) from Australian Plants, journal of the Association of Societies for Growing Australian Plants, December 1993
Earl, G, Stelling F, Titcumb, M & Berwick, S (eds.) 2001, Revegetation Guide for the Goulburn Broken Catchment, Dept. of Natural Resources & Environment, Melbourne, VIC.
Gray, M & Knight, J (eds) 2001 (3rd edition), Flora of Melbourne: a guide to the indigenous plants of the greater Melbourne area, Hyland House, Flemington, VIC.
Greening Australia Victoria (comp.) n.d., Indigenous plants for North Central Victoria: a revegetation guide, Dept. of Natural Resources & Environment, Melbourne, VIC.
Gunn, B 2001, Australian Tree Seed Centre: Operations Manual, CSIRO Forestry and Forestry Products, Canberra, ACT.
T.D. Macfarlane, L. Watson and N.G. Marchant (Editors) (2000 onwards). Western Australian Genera and Families of Flowering Plants. Western Australian Herbarium. Version: August 2002. http://florabase.calm.wa.gov.au/.
Ralph, M 1994 (2nd edition), Seed collection of Australian native plants : for revegetation, tree planting and direct seeding, Bushland Horticulture, Fitzroy, VIC.
Ralph, M 2003 (2nd edition), Growing Australian native plants from seed : for revegetation tree planting and direct seeding, Bushland Horticulture, Fitzroy, VIC.
Semple, WS & Koen, TB 1996, ‘Effect of seedbed on emergence and establishment from surface sown and direct drilled seed of Eucalyptus spp. and Dodonaea viscosa’ in The Rangeland Journal, vol.19, pp.80-94.
Walsh, NG & Entwisle, TJ (eds.) 1996, Flora of Victoria, Volume 3, Inkata Press, Melbourne, VIC.
ACKNOWLEDGEMENTS
Information compiled for this note series was a result of extensive literature and plant record searches completed by Lucy Nuttal, with assistance from Michelle Butler, Christine Gartlan and Anne Ovington.
To contribute to or provide feedback on this note, please email the Corangamite Seed Supply & Revegetation Network coordinators:
Michelle Butler, Dept Primary Industries michelle.butler@dpi.vic.gov.au Chris Gartlan, Ballarat Region Seedbank, GAV christine.gartlan@dpi.vic.gov.au.
DISCLAIMER 2006
The authors do not guarantee that the information is without flaw of any kind or wholly appropriate for your purposes and therefore disclaims all liability for any error, loss or consequence which may arise as a result of you relying on this information.