A low-lying to erect shrub that typically grows to 1.5 m (often smaller) with glabrous and often spiny stems.
It grows naturally in New South Wales, south from around Merriwa, through Kandos and Lithgow, as well as the northern Blue Mountains, with some records in Sydney, then with a disjunction to the Lake Burragorang area and Southern Highlands as well as Dapto. It then grows in high concentrations at Nowra, Jervis Bay and Morton National Park, with scattered records along the rest of the South Coast and Tablelands. It grows in Victoria, north of Traralgon, as well as west of Melbourne, to around Ballarat and Bendigo.
It grows in heath as well as dry sclerophyll woodlands and forest, on sandstone and sandy soils.
Dillwynia is a member of the “pea” family. This generally means that leaves are alternate with stipules at the base of the petioles. Dillwynia have simple and alternate leaves, with stipules present and minute, or absent. Leaves can be flat, terete or triangular in cross-section and often twisted. In this species, leaves are linear to narrow oblong or spatula-shaped, to 10 mm long and about 0.5 mm wide, on a petiole about 1 mm long, slightly twisted, smooth or with minute tubercules.
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 Dillwynia, flowers are yellow, or red and yellow (or orange/yellow) and are usually arranged singly or in small groups in leaf axils or on the ends of branchlets. The upper two of five sepal lobes are joined in a single “lip”. The standard petal is typically wider than high (a useful identification feature), and the keel is the same length as the wings. There are very small leafy bracts present on the common peduncle (which can fall early or be persistent) and bracteoles on flower pedicels (below the calyx).
In this species, the flowers are arranged singly, at the terminals or in leaf axils near the ends of branchlets, yellow in colour with the standard to 10 mm long and bearing red markings. The keel is also red. Flowering primarily in late-winter and spring.
The fruit of all peas is a pod. In this species, they are approximately 7 mm long with smooth seeds.
This species is not commonly known to be cultivated and not a lot of information is currently available. It may be more readily cultivated in the future. It is found naturally on sandstone and sandy soils, and so may need similar conditions in a garden to thrive.
In a garden situation, Dillwynias are not overly common in cultivation and only occasionally grown by enthusiasts. They are generally suited to well drained soils in a sunny or semi-shaded position and most will tolerate heavy pruning.
Propagation from seed is relatively easy following pre-treatment to break the physical dormancy provided by the impervious seed coat. Pre-treatment can be carried out by abrasion or soak in near-boiling water for about 30 seconds, before cooling rapidly under flowing cold water. Alternatively soak in cold water for several hours. Dry to prevent rotting before sowing. Germination occurs in 3-4 weeks.
Cuttings strike reasonably well using firm, current season’s growth.
Dillwynia is a genus of about 40 species of flowering plants endemic to Australia and occurring in all Australian states and the Australian Capital Territory (except the Northern Territory). They are generally small to medium-sized shrubs. They are often known by the name of ‘Eggs and Bacon’ or ‘Parrot-peas’ because of their bright yellow and reddish tints of the flowers. NSW currently has about 22 taxa.
Dillwynia plants (as well as Acacia) are often colonising species which germinate quickly after fires to stabilize the soil and to provide nitrogen (all are legumes able to “fix” nitrogen from the atmosphere in nodules on their roots).
The following link is a list of Dillwynia species accepted by the Australian Plant Census and Plants of the World Online as at May 2021:
Dillwynia spp. will mostly regenerate from seed after fire.
Dillwynia – honours Lewis Weston Dillwyn (1778-1855) was a British porcelain manufacturer, naturalist and Whig Member of Parliament (MP). He was also renowned for his published works on botany and conchology,
ramosissima – from the Latin, ramosissum, meaning “branched”, referring to the much-branched habit of the plant.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Dillwynia ramosissima profile page
Wikipedia – Dillwynia ramosissima profile page
Denise Greig (1996). Flowering Natives for Home Gardens, Angus & Robertson.