Rural Lands Protection Fund brochure:
PESTFACT PO33/E0194/P0294
Identification of Prickle Bushes

Parksonia
Mesquite
Prickly Acacia
Mimosa bush

Four prickly leguminous trees are woody weeds of semi-arid areas. Because two or more are often present in the same area, land managers should correctly identify them before considering control measures.

With practice, mature plants of the four species can often be recognized from a distance by their overall shape and sometimes their foliage colour. However, because many trees are not the "standard" shape of colour, quick visual identifications from afar are not always correct. All four species produce spines, yellow flowers, and bean-like seed pods. For positive identification a tree must be examined closely.

Distinguishing characters:

Fortunately, the four prickly bushes or trees can be easily distinguished, as follows:

• Parkinsonia has leaves that are a flattened green leaf stalk with small leaflets moderately spaced along each side. The other tree weeds all have ferny type leaves.
• Mesquites are easily distinguished from prickly acacia and mimosa bush by the flower clusters - "lambs tails" for mesquite versus small round flower clusters for the other two.
• Prickly acacia and mimosa bush are easily distinguished by their seed pods - constrictions between the seeds for prickly acacia versus a cylindrical pod for mimosa bush.

If there are no flowers, pods alone can be used to distinguish mesquites, prickly acacia and mimosa bush.

If there are no flowers or pods, bark colour can be used, with some expertise:

• Parkinsonia plants of all ages have green bark
• The young bark of mesquite is often green and/or dark red
• The young bark of prickly acacia has a tinge of orange or green
• In the mimosa bush, the young bark is grey with white spots.


Description
Parkinsonia (Parkinsonia aculeata)

Other common names: Jerusalem thorn, jelly bean tree

Parkinsonia is a thorny shrub or small tree which can grow to 10m tall but is usually around 4m tall. It can be either single or multi-stemmed. The leaves are different to the ferny leaves of prickly acacia, mimosa and mesquite. They consist of a fattened leaf stalk up to 30cm long with tiny oblong leaflets in rows along each side. Sharp, recurved spines up to 1 cm long are found on the stem at the base of each leaf.

The stems, branches and often the trunk of parkinsonia are characteristically green. Perfumed flowers are mainly yellow except one of the five petals has an orange spot or is completely orange. Flowers are arranged in drooping sprays about 20cm long. The pods are straight, 5 to 10cm long, straw coloured, with long constrictions between the seeds.