The Galápagos are famous for their reptiles and birds
but much of the islands' flora is equally interesting
and it's just as vulnerable to the impact of humans.
Over the last centuries, almost 500 species of plant
have been imported into the Galápagos,
some for agriculture, some for gardens
and some by accident.
Like the wild goats who compete with indigenous tortoises for food,
so these newcomers compete with local plants
for sunlight, soil and water.
Santa Cruz, for example, is home to a unique species of plant
called miconia, which is only found on one other island.
Today, it is under threat from the red quinine tree.
First brought onto the island in the late 1940s,
the red quinine tree is very hardy
and it reproduces so rapidly that there were worries
that it might wipe out the whole of the miconia zone.
Today, the National Park Service are actively engaged in a programme
to eradicate red quinine...
...injecting any seed-bearing trees
with cartridges filled with herbicide.
It's expensive, time-consuming work and there are many trees to kill
but scientists are optimistic that they may eventually eradicate
the most damaging newcomers.