Hardenbergia violacea is a well known climber or twining shrub with stems reaching up to 2 metres long.
It has a large geographic range, growing all over the coast, tablelands and western slopes of NSW, and just into the western plains (i.e. Griffith). It exhibits a range of forms from prostrate-running, to climbing to more of a twining shrub. It extends into Queensland, growing as far north and west as the Cairns region. It grows commonly through most of Victoria (except the north-west) and the south coast area of South Australia. It also grows in the south-west of Western Australia.
It is found in a range of habitats and soil types, from dry to wet sclerophyll woodland and forest, shrublands and heathlands as well as grasslands and regenerating areas; on sandy to clay soils as well as loams.
Hardenbergia is a member of the “pea” family. This generally means that leaves are alternate with stipules at the base of the petioles. Hardenbergia spp. generally have compound tri-foliolate and alternate leaves, with stipules present. In this species, leaves appear simple and alternate. However, if one looks closely, the other two leaflets making up the compound leaf have been reduced to tiny vestigial leaflets at the base of the main ‘leaf’. Compound leaves that have been reduced to one leaflet are called ‘uni-foliolate’ compound leaves (which basically appear simple). Two stipules are present where the leaf petiole joins the stem. The ‘leaves’ are glossy green, with prominent veins, to 10 cm long and 5 cm wide, lanceolate to ovate in shape, mid to dark green or blue-green with much paler undersides.
Flowers are, of course, pea-shaped (a term sometimes used is papilionate), with 5 petals in a fixed arrangement; the main back petal is called the “standard”, two lateral petals called “wings” and two fused petals at the bottom called the “keel” (in which the anthers and one carpel tend to be hidden). In this species, they are purple (rarely pink or white) with conspicuous green markings on the standard, up to 1 cm across, produced in racemes to about 15 cm long, appearing in mid-winter to early spring.
The fruits of all peas is a pod. In this species, they are oblong, to 45 mm long by 15 mm wide, carrying about 6-8 seeds, each to 5 mm long.
A very popular native plant to grow and many gardeners think it is a ‘must have’. Typically grows well in any garden, although there are a range of forms which are now in propagation. Local forms may be best suited to most gardens.
H. violacea could be grown as a ground cover if it is denied access to other plants or objects to clamber over. It does not usually cause an issue for other plants when allowed to ramble through a garden. It may need some pruning after flowering to keep it under control. Climbing forms can be grown on trellises and short fences.
Very hardy once established, it tolerates frost and drying out. Sometimes, it can be short-lived. The flowering display in winter-spring is always a joy.
Plant in a sandy to clay soil. It can take some enrichment and an amount of poor drainage.
It has become a very popular plant overseas.
It is subject to leaf ‘skeletonising’ every now and then where the leaf tissue is attacked by an insect pest.
Propagate from seed that should be treated with boiling water to soften the seed coat. Cuttings strike readily.
Cultivars should be propagated from cuttings to preserve their ‘true-to-type’ characteristics.
There are a number of cultivars. ‘Mini Haha’ is an upright form. ‘Alba’ has white flowers. ‘Happy Wanderer’ is a very vigorous climber with purple flowers.
Hardenbergia is an Australian genus with 3 species. One is endemic to Queensland and one to Western Australia. NSW has H. violacea naturally and also H. compotoniana (from WA) as a weed-species.
This species regenerates readily after fire from the seedbank. Reshooting of root-stem bases may be possible.
Hardenbergia – named after Franziska, the Countess of Hardenberg (1796-1853) (Austrian) who assisted other botanists in curating and publishing their Australian plants and had a keen interest in Australian flora.
violacea – Latin meaning “violet”, referring to the colour of the flowers.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Hardenbergia violacea profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Hardenbergia~violacea
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.
Gardening with Angus – Hardenbergia violacea profile page https://www.gardeningwithangus.com.au/hardenbergia-violaceae-native-sarsparilla/