We have two local Darling Peas which are easy to mistake for each other. Both are very pretty, easy-to-grow garden plants, and both have the typical Swainsonia seedpods, which begin green, and develop a pretty pink blush on their sunny sides. The mature pods make good little boats to amuse children if weighted with a tiny pebble below the waterline. Ankle-biters with plenty of puff can have boat-races by blowing them across puddles.
Swainsona galegifolia
This is a multi-stemmed sub-shrub , with a clump of stems growing from a single crown.
A well-grown plant can have several dozen stems, about waist-high, and branching. Each stem lasts a few years, but the plant is constantly being renewed by new stems, and has a few flowers for much of the year. Tidy gardeners will cut off the old ones each season.
This drought-hardy plant is uncommon in our local area, but is found on the edges of rainforests, and grows particularly well in red soil.
Swainsona queenslandica
The Darling peas we usually see on, red and black soils around Toowoomba are this species. A very drought hardy plant, it spreads by underground rhizomes, and is the plant we see around Toowoomba. Its unbranched stems only grow to about 30cm high. It is very easy to grow from a piece of rhizome such as the one below. (My little finger marks the point at which the stem appears above the ground.)
This plant looks its best if it’s cut back to the ground each year after the spring/summer flowering season.
If well-watered this is a vigorously spreading plant. People with tidier gardens than mine might like to have it contained by paths or buildings. Others will see it as a good plant to naturalise in a rough, or perhaps occasionally-mown, area.
It is my favourite, being very showy at this time of year, and looks great mixed with yellowtop daisies, native geraniums, and native poppies.
Distinguishing Between the Two
Swainsona galegifolia and Swainsona queenslandica can be easily confused in the wild, because their flowers and leaves are rather similar.
Swainsona queenslandica has isolated stems, separated along its creeping underground rhizomes.
The difference is obvious in well-grown plants. However, in a rather skimpy plant with few straggly stems it can be difficult to know what's going on underground.
The distinction is clear, however, if the plants are in flower. The wings are distinctly different in length.
Swainsona galegifolia's wings are not more than 60% of the length of the keel.Swainsona queenslandica (below)has wings which are about the same length as the keel, or a little longer.
Locally, it has both red and pink forms.