\version "2.19.14"

\layout {
  \context {
    \PianoStaff
    \consists #Span_stem_engraver
  }
}

\score {
  \new PianoStaff <<
    \new Staff {
      \voiceTwo
      \crossStaff e'8 \p
    }
    \new Staff {
      \clef bass
      e8
    }
  >>
}