September 2014. Three weeds from the lowland gardens of Papua New Guinea sent from OPRA the oil palm research organisation.
The image (top, right) looks like Elephantopus mollis or ‘tobacco weed’ (Asteraceae). It can become quite a significant pest of pastures. It has been observed in other parts of PNG. Some information is on the Queensland government website: http://www.daff.qld.gov.au/plants/weeds-pest-animals-ants/weeds/a-z-listing-of-weeds/photo-guide-to-weeds/tobacco-weed
There is also a smaller species, Elephantopus scaber, which is not as invasive but can be mistaken for E. mollis.
In the earlier email, the first of the two weeds illustrated looks like a Crotalaria (Fabaceae) (top, left) but the image isn’t clear enough to be certain. It is likely to be Crotalaria montana which is widespread in PNG and northern Australia and is considered native in both regions.
The second weed in that email looks to be a species of Spermacoce or Borreria (Family Rubiaceae) (image below). Another possibility for this weed is Diodella sarmentosa, tropical buttonweed. This was formerly known as Diodia sarmentosa. Definitely worthwhile trying to get a specimen identified.This group can be very difficult to identify correctly, even with a specimen, so it was suggested to get a specimen to the Lae herbarium.