1st looks like False Solomon's Seal (Maianthemum racemosum).
Looks like Black Medic (Medicago lupulina).
Looks like Organ Pipe Cactus (Stenocereus thurberi). edit - Didn't notice you were in Australia. not sure what it is.
Good work. Didn't realize 1 and 2 were the same. They look like different plants from the photos. I think you are right, photo 2 does look like...
Making a positive ID of Apiaceae species from photos alone for 1 and 2 can be tricky, especially for young plants. Always want to rule out Conium...
If so, it's definitely not a native Cherry. I'm not sure what it is.
Information on it's edibility can be found here: http://www.eattheweeds.com/american-nightshade-a-much-maligned-edible/
Those on this forum have a lot of expertise and many of them are specialists. It's interpretation of the photos that is most important (plus the...
That is not an easy question to answer. In my opinion, experience is king. It's going to take effort - sorry, there's no other way. Ask questions,...
Amaranthus. Uncertain for sure of species, but possibly Amaranthus hybridus.
Helianthus grosseserratus (Sawtooth Sunflower)?
Sure looks like Monarda fistulosa, especially if the flowers are in the 1.5-2.0 inch range. It's a plentiful species in my area.
Black Mustard or Field Mustard generally don't grow in wetlands; however, that doesn't mean they will never be found in that type of environment....
Lobelia, probably L. siphilitica.
It looks like Brassica of some type. The leaves in the foreground are unusual if they are from the same plant. I'm not 100% about the...