An erect to low-lying, heath-like shrub to a height of 1.5 metres, with stiff branches that are hairy, especially when young.
It has a large range over the approximate eastern half of NSW, through the western slopes and tablelands, but only the central and south coast areas. It extends into south-east Queensland, almost all of Victoria and Tasmania and into the east of South Australia.
It grows in heath, shrubland as well as dry sclerophyll woodland and forest, on a variety of soils, from sandy to clay. It is known to be a variable species.
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 20 mm long and less than 1 mm wide, with tubercules or smooth, hairy or not.
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, flowers are usually arranged in pairs in the leaf axils (sometimes singularly or in larger groups), red-orange through to yellow, with the standard petal to 12 mm long, often wider than long, with a red base. The wings are reddish in colour; occurring from September to December.
The fruit of all peas is a pod. In this species, they are approximately 6 mm long, with seeds reticulate.
Not widely cultivated but well worth a try. This species is a very floriferous shrub and worth growing in groups of 3 or more, to highlight the flora display. Is also frost hardy. Grows well beneath established trees and in containers. Prune after flowering to maintain shape. Found naturally on a range of soils so it may be tolerant in a range of garden situations.
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.
Seed is available commercially.
Recent taxonomic revisions (2021) have occurred involving the Dillwynia genus. It seems Dillwynia rudis has been lumped in with this species as a subspecies. Four subspecies are currently recognised in NSW:
Intermediates occur between D. sericea subsp. sericea and subsp. rudis, especially in the Central Tablands and the Central western slopes, where the two subspecies overlap. This complex continues to undergo revision.
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.
sericea – Latin sericeus meaning “silky” – referring to the hairs on the young branches.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Dillwynia sericea profile page
Wikipedia – Dillwynia sericea profile page
Cronin, L. (1990). Key Guide to Australian Wildflowers. Reed Books Pty Ltd.