Self guiding identification sites enable searches by growth habit/weed type: tree, shrub, vine, herb, grass, aquatic (water) or bulbous succulent.
The flower, seed or fruit is often necessary for identification
Australian Government Weeds Identification Tool – look up weeds by name, place, growth habit and flower colour.
PlantNET – look up plants including weeds by place, name, classification. This identification tool maintained by the staff of the National Herbarium of NSW includes identification ‘keys’
New Weeds in Sydney