Only a fraction of
all the existing life forms have been
identified. To fill in our picture
of the living world, biologists search
for new species—groups of organisms
that reproduce with one another and
share a common evolutionary history.
Botanist Nancy Garwood is identifying
the species within a group of
closely-related plants that grow in
Belize. To do this, she has to look
at everything from their outward appearances
to the structure of their DNA.