Acacia mearnsii
Environmental Weed (2024)
Common names
black wattle
Biostatus
Exotic
Category
Vascular
Structural class
Trees & Shrubs - Dicotyledons
Flower colours
Cream, Yellow
Detailed description
Shrub to large tree, twigs ribbed or angled. Leaves 2-pinnate, pinae in 9-18 pairs, pinnules close-set, dark green and in 20-60 pairs. Inflorescence consists of many pale creamy yellow globbose heads arranges in racemes. Seed pod straight or somewhat curved, up to 90 x 7 mm, usually constricted around each seed.
Similar taxa
A. mearnsii is easily distinguished by the dark green foliage, creamy yellow flowers and the most pinnules of all the 2-pinnate wattles naturalised.
Habitat
Waste places, scrubland, pasture, riverbanks
Conservation status
Not applicable
Detailed taxonomy
Family
Ecology
Flowering
July, August, September
Year naturalised
1981
Origin
S.E. Australia, Tasmania
Reason for introduction
Ornamental
Tolerances
Can tolerate dry conditions and frosts to about -7 degrees.
Life cycle and dispersal
Perennial. seeds have been known to germinate after 90 years. Seed is produced in large numbers in dark brown pods. Seed viability is estimated at 50 years. Mass germination is likely following fire, or mechanical disturbance. Saplings may coppice if cut, but does not sucker. Spread by people for firewood and as an ornamental tree. Seed dispersed locally by wind and gravity.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
UPL: Obligate Upland
Rarely is a hydrophyte, almost always in uplands (non-wetlands).
Other information
Etymology
acacia: Derived from Greek ‘akazo’ to sharpen, meaning point; spine or thorn.
Environmental Weed (2024)
This plant is named in a list of 386 environmental weeds in New Zealand 2024 prepared by DOC. 759 candidate species were considered for inclusion on this new comprehensive list of environmental weeds in New Zealand. The species considered were drawn from published lists of weed species, lists of plants that must be reported or managed by law if observed, existing national and regional programmes and agreements for pest management, and species already managed by the Department of Conservation (DOC). Candidate species were then assessed to see if they were fully naturalised and whether they have more than minor impacts in natural ecosystems. Read the full report here.
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
ACAMEA