# Tikz tree, how to draw arrows from child to parent

I want to (1) draw an arrow from child to parent [illustration in green color on the graph], (2) draw and outer arrow with text on it as shown in the figure below [illustration in red color].

Here is my code:

\documentclass{article}
\usepackage{tikz-qtree}

\begin{document}

\begin{figure}[!h]
\centering
\scalebox{0.9}{
\begin{tikzpicture}
[every tree node/.style={draw,circle},
level distance=1.25cm,sibling distance=.5cm,
edge from parent path={(\tikzparentnode) -- (\tikzchildnode)}]
\Tree [.\node[label=right:n,red] {nn};
[.\node[label=left:{$C_{O5}=C_{O1}*C_{O2}*C_{P5}$}] {5};
[.\node[label=left:{$C_{O1}=C_{P1}$}] {1}; ] [.\node[label=right:{$C_{O2}=C_{P2}$}] {2}; ]
]
[.\node[label=right:{$C_{O6}=C_{O3}*C_{O4}*C_{P6}$}] {6};
[.\node[label=left:{$C_{O3}=C_{P3}$}] {3}; ] [.\node[label=right:{$C_{O4}=C_{P4}$}] {4}; ]
] ]
\end{tikzpicture}
}
\end{figure}

\end{document}

• edge from parent path={[<-,line width=2pt,green!50!black](\tikzparentnode) -- (\tikzchildnode)} – Salim Bou Jun 3 '17 at 20:00
• Do you really want to draw over the equations to the left of the nodes? – cfr Jun 3 '17 at 21:29
• Thank you Salim, but it does not work. – Sari Jun 4 '17 at 9:54
• than you cfr, no actually what you did is perfect – Sari Jun 4 '17 at 9:55

You already have an answer for tikz-qtree in the comments, but here's an alternative using Forest, which I would use here because it is a tree.

By default, setting a tree with much larger labels and node content is problematic, because Forest ignores the labels when packing the tree. However, if we put the labels into more nodes, then we don't have to worry about setting the sibling separation manually to make room for them, as Forest will take care of the spacing for us.

Despite your image, I've avoided drawing the red arrow over the labelling, but you can adjust the placement if you really want that.

\documentclass{standalone}
\usepackage{forest}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{forest}
for tree={
draw,
circle,
edge+={Stealth-, green!75!black, thick},
},
before typesetting nodes={
for tree={
split option={content}{:}{content,label me},
},
},
label me/.style={
if level=0{
label=right:{$#1$},
}{
if n'=1{
insert after={[{#1}, math content, no edge]},
}{
insert before={[{#1}, math content, no edge]},
},
},
},
tikz+={
\draw [thick, red!75!black, -Stealth] (!r22.south) ++(-15pt,0) -- ([shift=(135:2.5pt)]!r2.north west) -- ([shift=(135:2.5pt)]!r.north west) node [midway, sloped, above] {text here};
},
[nn:n, red
[5:{C_{O5}=C_{O1}*C_{O2}*C_{P5}}
[1:{C_{O1}=C_{P1}}]
[2:{C_{O2}=C_{P2}}]
]
[6:{C_{O6}=C_{O3}*C_{O4}*C_{P6}}
[3:{C_{O3}=C_{P3}}]
[4:{C_{O4}=C_{P4}}]
]
]
\end{forest}
\end{document}