Edibility of ornamental Ipomoea batatas?

[Phred]

on for a few minutes to make the point how strongly
  he and his brothers felt that the United States should never
  be in a situation of having recourse to assassination.

Szulc's notes of the meeting state:
  JFK then said he was testing me, that he felt the same way -
  he added "I'm glad you feel the same way" - because indeed
  the U. S. morally must not be part (sic) to assassinations.

The Church Committee also heard testimony from Smathers who
stated that once when it was brought up in his presence
(presumably by the CIA friendly Smathers), Kennedy got so mad he
smashed a dinner plate and told him he did want to hear of such
things again (Alleged Assassination Plots p. 124). Smathers
furthered this portrait later when he stated that:
  President Kennedy seemed "horrified" at the idea of
  political assassination. "I remember him saying. . .that the
  CIA frequently did things he didn't know about, and he was
  unhappy about it. He complained that the CIA was almost
  autonomous. He told me he believed the CIA had arranged to
  have Diem and Trujillo bumped off. He was pretty well
  shocked about that. He thought it was a stupi