Washington Post (NYSE: WPO) is extending its slate of online brands and adding an online news and commentary site called TheRoot, focused on a black audience, with news and commentary on politics and culture, and genealogy tools for readers, reports NYT.Henry Louis Gates Jr., a prominent writer and a professor of African and African-American studies at Harvard, is the editor in chief of the site.

The site will compete with other established sites such as AOL-owned BlackVoices.com, but is trying to position itself as a more highbrow alternative, instead of focus on entertainment, lifestyle and consumption. The site “will not have an explicitly black angle” but will address issues like health care and housing, the managing editor Lynette Clemetson said in the story. There are some parallels with WaPo-owned Slate..in fact Slate editor Jacob Weisberg advised on the launch of TheRoot.

More on the site from WaPo’s own story: The Root is WPNI’s second spinoff, and Post Co. Chairman Don Graham said he is considering others. Last year, the company launched Sprig.com, a site aimed at female users interested in green living. Today the company admitted that Sprig has grown more slowly than hoped, said WPNI publisher Caroline Little…the site will relaunch with a narrower focus and bigger marketing later this year.

• Everyone’s Green: WaPo’s Green Site; NatGeo; Hearst’s DailyGreen; Lime’s Green Blog Ad Network