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>
    <revisions rvcontinue="6" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page">
        <revisions>
          <rev user="Planteome wiki admin" timestamp="2011-07-11T19:41:42Z" comment="/* Welcome to the Planteome Annotation Wiki, a resource for annotated plant genotypes and phenotypes on the semantic web! */" />
          <rev user="MediaWiki default" anon="" timestamp="2011-08-03T00:16:58Z" comment="" />
          <rev user="Planteome wiki admin" timestamp="2011-08-03T19:06:23Z" comment="" />
          <rev user="Planteome wiki admin" timestamp="2011-08-03T19:06:40Z" comment="Reverted edits by [[Special:Contributions/Planteome wiki admin|Planteome wiki admin]] ([[User talk:Planteome wiki admin|talk]]) to last revision by [[User:MediaWiki default|MediaWiki default]]" />
          <rev user="Planteome wiki admin" timestamp="2011-08-03T21:58:42Z" comment="1 revision: Content Pages - migration to Test from Dev" />
        </revisions>
      </page>
    </pages>
  </query>
</api>