is this the same st .johns wort (Hypericum perforatum) that is the herbal
 alternative to synthetic anti-depressants and weight-loss drugs,
supposedly without the side effects?
if so, then there may be a more appropriate control strategy that could
benefit the outback economy: selective harvesting by humans coupled by
propagation via honeybee pollination...perhaps even pollen-trapping if
the active ingredient  (hypericin) is found in it, and maybe even a honey
crop, conceivably also medicinal?
here in florida(usa), a similar scenario has evolved with saw palmetto
(Serenoa repens), a native nectar source plant (so abundant as to be
considered a weed by some) whose berries have become a medicinal-herb
commodity (for prostrate gland problems, i believe) requiring state
regulation due to potential overharvesting...it yields both a palatable
honey in the spring and a sort of "honeydew" later on from the overripe
berries, but  i don't know if anyone has considered testing for
pharmacological activity (as in the case of manuka honey from new
zealand)...