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>
    <allfileusages afcontinue="Pink_Tip_Greasy_pods_full.jpg|71" />
  </query-continue>
  <query>
    <allfileusages>
      <f ns="6" title="File:Lohrey&#039;s Special cotyledons.jpg" />
      <f ns="6" title="File:Lohrey&#039;s Special seeds.jpg" />
      <f ns="6" title="File:Lohrey&#039;s Special seeds.jpg" />
      <f ns="6" title="File:Lohrey&#039;s Special seeds fresh.jpg" />
      <f ns="6" title="File:Lohrey&#039;s Special seeds fresh dry.jpg" />
      <f ns="6" title="File:Lohrey&#039;s Special sprout.jpg" />
      <f ns="6" title="File:Lohrey&#039;s Special vine 2.jpg" />
      <f ns="6" title="File:Pink Tip Greasy flower bud and old.jpg" />
      <f ns="6" title="File:Pink Tip Greasy flower mid.jpg" />
      <f ns="6" title="File:Pink Tip Greasy leaf.jpg" />
    </allfileusages>
  </query>
</api>