The Swainsona Files

The Swainson-peas are beautiful plants, difficult to propagate and mostly threatened in Victoria. In the Mallee we have several species, including: Small-leaf Swainson-pea (Swainsona microphylla); Silky Swainson-pea (Swainsona sericea); Dwarf Swainson Pea (Swainsona phacoides); and Hairy Darling-pea (Swainsona greyana).

Small-leaf Swainson-pea (Swainsona microphylla)

Habit: Low-growing perennial herb to 60 cm high.

Leaves: Compound leaves 5-15 cm long, comprised of 21-41 leaflets, sometimes hairy. Each leaflet is round: 1-5mm long and wide, with the tips notched or with a short point.

Flowers: Racemes of 10-25 flowers. Petals are white, pink or purple.

Seed pods: Hairless seed pods are nearly round, 5-10 mm long and 3-8 mm wide, containing about 8 seeds.

Habitat: Light soils on sand hills and sand plains, usually near the Murray River. This is the most common Swainson-pea on Raakajilm.

Silky Swainson-pea (Swainsona sericea)

Habit: Low-growing perennial herb to 20 cm high.

Leaves: Hairy, compound leaves 2-7 cm long, comprised of 5-13 leaflets. Each leaflet is 5-15mm long and 1-3 mm wide with acute apices.

Flowers: Racemes of 2-8 flowers. Petals are purplish, with the keel 7-10mm long (shorter than the wings). A key feature is the style tip which is bent.

Seed pods: Hairy seed pods are 10-17 mm long and 4-8 mm wide, containing about 20 seeds. Stipe (stalk attaching pod to plant) is about 4 mm long.

Habitat: Grassland and grassy woodland.

Dwarf Swainson Pea (Swainsona phacoides)

S. sericea and S. phacoides are difficult (for me) to tell apart. The following describes S. phacoides compared to S. sericea

Habit: Can be taller, up to 30cm high.

Leaves: Generally, leaves are longer (5-10 cm long) and leaflets are larger 5-30 mm long x 1-5 mm wide. The apices are often blunt or notched.

Flowers: Racemes can have more flowers (1-10). Petals are a more reddish-purple. The keel is generally longer at 10-15 mm and is longer than the wings. The style tip is not bent, being slender and straight.

Seed pods: Seed pods are often longer, 10-30 mm long and 4-12mm wide, with about 40 seeds. The stipe is very short, about 0.5 mm long.

Habitat: Mostly on low dunes or sandy rises associated with lakes or the Murray River, occasionally on plains with heavier soils, rarely in deep sand mallee

Hairy Darling-pea (Swainsona greyana)

Habit: Erect, perennial shrub to 2m tall.

Leaves: Compound leaves 10-15 cm long, comprised of 17-21 leaflets. Each leaflet is 10-40 mm long and 4-10 mm wide with rounded apices. Upper surface is hairless and lower surface is lightly hairy.

Flowers: Racemes of 12-20 flowers. Petals are white, pink or purplish, 20-25 mm long.

Seed pods: Hairless seed pods are 30-50 mm long and 8-12 mm wide, containing about 28 seeds. Stipe (stalk attaching pod to plant) is about 4 mm long.

Habitat: Heavy soils in riverine woodland. We have introduced a population of this species to Raakajilm wetland and it is growing well.