You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <alltransclusions gatcontinue="Botanics_info|426" />
  </query-continue>
  <query>
    <pages>
      <page pageid="9" ns="0" title="The Nexian DMT Handbook" />
      <page pageid="25" ns="0" title="Anadenanthera peregrina" />
      <page pageid="241" ns="10" title="Template:Botanics info" />
      <page pageid="304" ns="0" title="Phalaris arundinacea" />
      <page pageid="534" ns="0" title="Acacia angustifolia" />
      <page pageid="535" ns="0" title="Acacia angustissima" />
      <page pageid="629" ns="0" title="Acacia cultriformis" />
      <page pageid="646" ns="0" title="Acacia floribunda" />
      <page pageid="647" ns="0" title="Acacia filiciana" />
      <page pageid="648" ns="0" title="Acacia farnesiana" />
    </pages>
  </query>
</api>