Family: Fabaceae
Common name: Hop wattle; Straight wattle
Category:1a NEMBA
Description
Acacia stricta (Andrews) Willd. is an erect shrub or small tree, 1,8 m high. Branches angled or flattened. Leaves narrow, elliptic, up to 12 cm long, prominent midvein and net-venation. Flowers yellow balls held close to the stems, occurring in groups of 2-4 in the axils of the leaves, appearing in spring. Pods straight up to 100 mm long and 5 mm wide. Seeds coat hard, the seed stalk expanded at one end but does not encircle the seed. Hop wattle might be mistaken for rooikrans (Acacia cyclops) or long-leaved wattle (Acacia longifolia). The differences between these species are tabulated below.
| Acacia stricta | Acacia cyclops | Acacia longifolia |
| Shrub or small tree
Leaves erect, rounded, prominent midvein and net venation |
Leaves with 305 prominent longitudinal veins | Shrub or tree, Leaves erect, spreading
Flowerheads cylindrical, galls on stems |
 |
 |
| Acacia stricta leaves | Acacia stricta flowers |
Distribution
Hop wattle is native to Australia (Victoria, New South Wales, Tasmania).
How it spreads
Seeds with sporadic strong winds and also appears to be easily dispersed via human activities and soil movement (most likely road construction). However, the majority of the seeds accumulate under the tree canopy.
History in South Africa
Hop wattle was probably introduced to South Africa as an ornamental plant and for soil stabilisation and has recently been recorded in the Knysna area (Western Cape), mostly on plantation land owned by MTO forestry.
Environmental and economic impact
Hop wattle is a fast growing and drought tolerant species, which can withstand both low and high temperatures. It forms persistent seed banks, and seedlings may continue to emerge for many years after the plant has been removed. The species is also considered a high risk species in terms of invasiveness. It invades roadsides, watercourses and gaps in plantations.
How to eradicate
Hop wattle is currently controlled by uprooting or cut-stump treatment using a glyphosate herbicide. There is no herbicide or biological control agent registered for this species in South Africa.
What can you do to help?
Report sightings of these plants to the Invasive Species Programme at SANBI. We will need to know its locality (the exact locality, supply a photograph, any landmarks or GPS information if possible).
Contact details
Ruqaya Adams or Alex Marsh
Email: invasivespecies@sanbi.org.za
Tel: 021 799 8403/4
References
- South African Plant Invaders Atlas. 2010. SAPIA News no. 8. ARC-Plant Protection Research Institute. Available on line at: http://www.dargieconservancy.org.za/documents/sapia08.pdf
- Broughton, V.H.1986. Phyllode structure, taxonomy and distribution in some Australian acacias. Australian Journal of Botany 34: 663-674. Available on line at: http://plantnet.rbgsyd.nsw.gov.au/PlantNet/WattleWeb/refs.php
- South African plants invaders atlas database. ARC- Plant protection research institute, Pretoria, South Africa.
- Pheloung P. C., P. A. Williams and S. R. Halloy. 1999. A weed risk assessment model for use as a biosecurity tool evaluating plant introductions. Journal of Environmental Management 57: 239-251.