It is better to think of life as a property of a planet, as far as we know. Biospheres are probably the unit, not organisms or a few small groves scattered on opposite sides of a planet. Obviously these life forms we are seeing are able to survive in what would be, for us, totally inhospitable conditions. Clearly there must be some source of free energy on these planets, and materials suitable to dissipate that free energy. The life forms that we see may be inappropriate for the conditions seen on these planets (we don't know!). But the argument that flora, if it exists, should be confined to a few tiny places just doesn't ring true.
Here's a screenshot: