African Scurfpea; refers to its country of origin and being in the pea family.
Psoralea is from the Greek psoraleos meaning scabby and referring to the black oil glands immersed in the leaf tissue. Pinnata refers to the pinnate leaf structure.
Other Names:
Blouker
Blue Broom
Blue Butterfly Bush in Tasmania
Blue Pea
Blue Pine
Blue Psoralea because of its blue flowers.
Cut-leaved Psoralea in New Zealand.
Dally Pine in New Zealand.
Psoralea after the genus name.
Scurf Pea
Taylorina because the Taylor family probably imported it as a ornamental plant.
Summary
African Scurfpea is a many branched, perennial shrub or small tree to 4 metres high with dark green foliage. The leaves have 5-11 very narrow, leaflets that are 2-3 cm long and dotted with tiny black glands. There are small clusters of fragrant pale blue and white pea flowers and each flower is about 1 cm long and on a slender stalk. The seed pods are small at only 4-5 mm long.
Originally introduced from South Africa as a source of nectar for bees, African Scurfpea has become a common weed around Albany particularly along roadsides and creeklines. It extends west of Denmark and flowers in spring and early summer.
Description
Cotyledons:
Two.
Leaves:
Dark green. Alternate, crowded, 30-50 mm long. Each leaf has 5-11 leaflets arranged like a feather (pinnately compound).
Stipules - 2.
Petiole - yes
Leaflets - Mid to dark green, 20-30 mm long by 1-2 mm wide, cylindrical, thick, channelled on the upper side, dotted with black stalkless glands. Soft. Pointed tip. Parallel sides. Tapering to parallel base. Downy hairy on both sides.
Stems:
Erect. Stiff. Mainly straight. Up to 4 m long. Round. Initially green to greyish turning dark brown with age. New growth sometimes has soft fine hairs.
Branchlets ribbed and sparsely to moderately hairy.
Flower head:
Flowers in leaf axils crowded towards the end of branchlets. Often single but up to 7 flowers have been reported in each axil (Tucker and Sturton, 1991). Inflorescence is a dichasial cyme. A pair of partly joined floral bracts are midway on the flower stalks.
Flowers:
Blue and white, pea type, 12-15 mm long, fragrant. Bisexual. Flowers have a cupulum (protective cap) around the flower during development. Psoralea is the only genus with a cupulum in the legumes.
Ovary -
Calyx - 5 equal, triangular lobes, 6-8 mm long, 10 ribbed with black stalkless glands.
Petals - 5. Standard petal is 9-11 mm long. Top half of the standard is blue, lower half is white and the wing petals are white.
Stamens - 10 of which 9 are fused and one partially fused.
Anthers - Uniform.
Fruit:
Stalkless pod which doesn't split on ripening. 4-5 mm long by 2.5-3 mm wide, black, wrinkled. Single seeded.
Seeds:
Dark brown. 2-4 mm long.
Roots:
Shallow, woody, branching taproot.
Key Characters:
Shrub
Dark green compound leaves.
Several linear leaflets with tiny black glands.
Blue and white pea-type flowers.
9 fused stamens and 1 free stamen
Adapted from J. Wheeler.
Biology
Life cycle:
Perennial shrub, up to 4 m high. Germinates mainly in winter and spring and grows vegetatively very quickly. It may produce flowers in November/December of it second season. In later seasons it produces large quantities of seed. It usually lives 10-15 years.
Physiology:
Tolerates seasonal dry spells, frost to around -40C, salt, wind, sea spray, grazing.
Tolerates grazing once established.
Grows best in full sun to partial shade.
Fixes atmospheric nitrogen.
Reproduction:
By seed.
Flowering times:
September to December.
Spring to early summer in the south west of WA.
Spring to early summer in south east Australia with occasional flowers at other times
Seed Biology and Germination:
After fire or clearing, large numbers of seedlings emerge. It is not reliant on fire for good germination.
Produces thousands of seeds per year.
The seed can remain dormant for at least 8 years and large soil seed banks are recorded under old infestations.
Disturbance or fire leads to mass germinations.
Vegetative Propagules:
None. Young trees with trunks less than 50 mm diameter will coppice. Older trees rarely coppice when felled.
Hybrids:
Population Dynamics and Dispersal:
Dispersed by seeds mainly in water flows. Road making machinery spreads it along road verges. Dumped garden waste is also another major method of spread.
Spread by birds, mammals and possibly by ants.
In the Albany region of WA it appears to be invading new areas at a rate of 0.5-1 Km per year.
A massive germination of seedlings usually occurs after fire or disturbance.
Origin and History:
Southern Africa.
Introduced to Australia as an ornamental plant.
Distribution:
ACT, NSW, SA, VIC, WA.
Abundant around the Albany area in WA and slowly invading surrounding roadsides and wetter areas. Other major infestations are in southern Victoria and north and eastern Tasmania.
New Zealand.
Courtesy Australia's Virtual Herbarium
Habitats:
Prefers wet areas and creek lines. It is tolerant of waterlogging. It will grow on well drained soil but is usually displaced by other species over time. Often seen on roadsides because it is intolerant of heavy grazing.
Climate:
Temperate.
Soil:
Most abundant on poorly drained soils. Common on sandy, peaty and duplex soils.
Tolerates a wide range of soils from sands to clays.
Invasive weed of the South Coast of WA and spreading elsewhere.
Weed of roadsides, plantations, drains, streams, wetlands, remnant vegetation, recreational and industrial areas and wastelands. Of little economic significance in grazing and cropping areas because it does not tolerate cultivation or grazing.
Environmental weed occurring mainly on disturbed areas in urban bushland and national parks.
It often grows in thickets excluding all other species and increase soil nitrogen levels which can reduce the persistence of some native species.
Listed as a "Garden Thug".
Major host for Golden dodder.
Toxicity:
Not reported to be toxic.
Legislation:
Not declared in Australia.
Management and Control:
Grazing provides effective control of seedlings. Felling or slashing provides good control of large plants but plants less than 1 m tall sometimes regrow. Metsulfuron, Garlon, Grazon, Access and glyphosate provide good control of mature plants when applied as overall treatments. Access provides good control as a cut stump or basal bark treatment.
Unless it is very hot, fire generally makes the infestation worse due to resprouting from the base of mature plants and increased germination of seed.
A hot fire can destroy old plants but usually leads to a massive seedling germination which will require controlling.
Thresholds:
Eradication strategies:
It will take many years to control infestations because of the large dormant seed banks. New infestations should be controlled immediately to prevent the build up of a hard seed in the soil.
Aerial spray large trees with 80 g/ha of metsulfuron(600g/kg) plus 0.25% Pulse® in spring to early summer or fell, slash or bulldoze these trees then burn in autumn.
Treat seedlings in early summer with 50 g/ha of metsulfuron(600g/kg) plus 0.25% wetting agent for partially selective control or 6 L/ha glyphosate(450g/L) for non-selective control. For hand spraying use 1 g metsulfuron(600g/kg) plus 25 mL Pulse® in 10 L water or 100 mL glyphosate(450g/L) in 10 L water and spray foliage until just wet.
Individual trees can be controlled by applying a mixture of 200 mL Access® in 10 L diesel to the lower 300 mm of the trunks.
Trees with trunks that are less than 20 mm thick tend to re-sprout when cut.
Juvenile trees about 1 m tall can usually be pulled successfully by hand. Smaller and larger plants tend to break and regrow. Cutting of slashing Plants with stems less than 50 mm tend to regrow after cutting or slashing unless treated with herbicide. Plants with trunks greater than 100 mm diameter can normally be cut close to the ground with little regrowth occurring.
A hot fire can kill plants but encourages a mass germination.
Grazing controls seedlings. It will take many years to deplete the soil seed bank. New infestations should be treated promptly before they spread.
Herbicide resistance:
None reported.
Biological Control:
This is a low priority because it is from a family that has many native plants and commercially valuable species.
Related plants:
Annual Verbine (Psoralea cinerea)
Bullamon Lucerne (Psoralea eriantha)
Emu Foot (Psoralea tenax)
Native Verbine (Psoralea patens)
Tall Verbine (Psoralea australasica)
The native plants have been re-assigned to the Cullen genus by some taxonomists.
Plants of similar appearance:
Woolly bush (Adenanthos spp.) grows in similar areas, but has red flowers and greyer leaves.
Young Pine trees look similar in the vegetative state.
References:
Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P72-73. Photo.
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #1032.5
Muyt, A. (2001). Bush Invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South East Australia. (R.G and F.J. Richardson, Australia). P209-210. Photos.
Tucker and Sturton, (1991)
South West Forest Flora (1997 in press)
Wheeler, Judy, Marchant, Neville and Lewington, Margaret. (2002). Flora of the South West: Bunbury - Augusta - Denmark. (Western Australian Herbarium, Bentley, Western Australia). P772. Diagram.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.
