Generally speaking, "Wikimedia" is an umbrella term, which refers as much to "the collection of websites that includes Wikipedia, Wikisource, Wikidata, etc." as it does to the foundation, so it needs to be a distinct entity.
The diagram above is imperfect in a few ways: It would be more accurate to have the Wikimedia community at the bottom. The Wikimedia Foundation's proper role is stewardship of the software and the technical core; it's not the basis out of which everything else springs. Most of the items at the top existed before the Wikimedia Foundation was created.
WikiBase and MediaWiki should be by themselves on one line.
"Wikimedia" is not a specific thing like many of the others here. I suppose it's another candidate for being at the bottom.
digraph { layout=dot rankdir=BT overlap=false concentrate=false bgcolor=lightblue // splines=" " "Wikimedia\nFoundation" -> Wikimedia Wikimedia -> { Wikipedia Wikidata Wikiversity "Wikimedia\nCommons" Wikibooks Wiktionary Wikisource } "Wikimedia\nFoundation" -> MediaWiki "Wikimedia\nFoundation" -> WikiBase MediaWiki -> Wikimedia MediaWiki -> WikiBase WikiBase -> Wikidata Wikidata ->{ Wikipedia Wikiversity "Wikimedia\nCommons" Wikibooks Wiktionary Wikisource } }
Wikipedia's Virtuous Circle
Another notable graph related to Wikimedia is the one (flawed) that emerged from Wikimedia's 2010 Strategic Planning process (which puts "technology" at the core), and the (in my view, corrected) version that puts "community" at the core. See this essay: What Wikimedia Needs in a Trustee 
(it was not titled with an eye to continual relevance, but the issues discussed there remain).
digraph { layout=neato overlap=false concentrate=false bgcolor=yellow // splines=" " Community [ color=red; pos = "2,2!"]; Reach [ pos = "0,0!" ]; Participation [ pos = "0,5!" ]; Quality [ pos = "2,2!" ]; "Tech\nPlatform" [ pos = "2,1!" ]; "Community" -> Reach "Community" -> Quality "Community" -> Participation Reach -> Participation Participation -> Quality Quality -> Reach "Tech\nPlatform" -> Community }
# Significant incidents in Wikimedia history
Spanish Fork
Wiki Loves Monuments
Wikipedians in Residence and GLAMwiki