Acacia retinoides (Swamp Wattle)


Michael's Opinion

Acacia retinodes is native to Australia and does not have thorns; non-Australian species do. It is a very showy shrub that is covered year round with golden yellow flowers. This species has a symbiotic relationship with soil bacteria that forms nodules on the roots. Even though this shrub is drought tolerant, salt and wind resistant, it is most likely to be killed in excessively harsh winters.

Botanical Information

FamilyFabaceae
GenusAcacia
Speciesretinoides
CategoryTropicals, Woody
TypeShrub (evergreen)
ReferencesFlora of Australia Volume 11A: Mimosaceae Acacia part 1. Melbourne ABRS/CSIRO Publishing: 281-282 2001. Googlebooks,Web.18 Jan. 2013..
OriginNative to southern Australia and Tasmania.
Ethnobotanical Uses
Disclaimer
Its fruit, seeds and leaves are used for dyes and for tannins.
Pronunciation

Details

USDA Hardiness Zone9 - 11
USDA Hardiness Ref.
Canadian Hardiness ZoneRequires cool season protection under glass.
Canada Hardiness Ref.
RHS Hardiness ZoneH4 - H1c
RHS Hardiness Ref.
Temperature (°C)(-4) - 10
Temperature (°F)25 - 50
Height6-10 m
Spread5 m
GrowthFast
Flowering PeriodSeptember, October, November

Description and Growing Information

General DescriptionBranches are sometimes pendulous, angled or flattened and glabrous. The phyllodes can be grey-green to glabrous with white bloom in colour. They are acicular, straight to thinly curved, sometimes with a hook at the tip.
ID CharacteristicThe leaves are acicular, thin and smooth. They can be green or glabrous with obscure veins and glands. The flowers are light gold to cream colour with globular heads on short racemes.
ShapeAn obconic or rounded tree with a spreading crown. spreads.
LandscapeBest used in a mixed shrub border, screen or windbreak.
PropagationEasily propagated by seed placed in boiling water for 12-24 hours, (allowing the water to cool during this period) and then sown before the seeds dry out. The boiling water softens the seed coat and allows quick germination which can vary from 1-4 weeks. Seed may be sown at any time of year although spring sowing seed seems to yield slightly more significant results. Once seedlings have produced their true leaves they may be pricked off into pots and transplanted according to growth rate. Cuttings may also work using half-ripened lateral shoots placed in a mix of equal parts sand and peat/compost and placed in a heated greenhouse under moist shade; cuttings are slow to root. Graft onto A. retinoides seed raised stock that is 18-24 months old and about 30 cm in height. Once the graft has taken remove the top growth from the understock the following spring.
CultivationCan tolerate a wide range of soil types however it prefers soils that have a pH of 5-7 in full sun. Drought tolerant, salt and wind resistant but is likely to be killed in excessively harsh winters. It will not grow in the shade.
PestsCan suffer from glasshouse red spider mite and mealy bugs but is generally pest free.
Notable SpecimensThe Royal Botanical Gardens, Burlington, Ontario, Canada.
HabitatOpen forests in poorly drained soils, inland from the coast in Australia.
Bark/Stem DescriptionThe green stems are smooth and thin.
Flower/Leaf Bud DescriptionFlower buds are 2-4-headed golden yellow globular clusters, 4-8 mm wide. Small flowers develop along a waxy, stout, hairless, curved axis approximately 25-90 mm long. Each cluster is on a 2-10 mm stalk. The prominent bracts are sub-circular and brown to black in colour with white fringes.
Leaf DescriptionPhyllodes are acicular in shape, straight to thinly curved and smooth, approximately 10 cm long by 1-2 cm wide. Grey-green in colour, and sometimes have a hook at the tip. Veins are pinnate from a prominent midrib, 3-22 cm long and 3-15 mm wide.
Flower DescriptionThe flowers are perfect. Globular heads have 18-50 small, golden yellow flowers, cream in colour, 3-5 mm in diameter. The heads grow on short axillary racemes are very fragrant and smell like almonds.
Fruit DescriptionFruit is oblong shaped, 18 cm long and 5-7 mm wide. A dull to slightly shiny, dark brown or black colour which turn red in autumn. The seeds are attached to the pod longitudinally by a long coloured double-folded funicle.
Colour DescriptionGolden yellow or cream flowers, cream or grey phyllodes. Pods are dull to slightly shiny, dark brown or black turning red in autumn.
Texture DescriptionSmooth textured plant.

Photographs