[Tex/LaTex] tikz trees: How to not draw a single edge

tikz-pgftikz-treestrees

I want to draw a tree and not draw specific edges. I try it like this 

\documentclass[preview]{standalone}
\usepackage{tikz} 
\begin{document}
   \begin{tikzpicture}[every node/.style={circle,draw}]
      \node (r) {$r$}
      child { node (T1) {$T_1$} }
      child { edge from parent[draw=none] node[draw=none] (ellipsis) {$\ldots$} }
      child { node (Tn) {$T_n$} };
   \end{tikzpicture}
\end{document}

This does drop the edge of the middle child, but for some reason shifts the node upwards. I want it to be placed at the same level as its siblings.
Is this doable without manually drawing a node between (T1) and (Tn)?

enter image description here

Best Answer

Edit: After clarifying, what is the problem, I suggest to try the following:

\documentclass[border=3mm,tikz,preview]{standalone}

\begin{document}
   \begin{tikzpicture}[every node/.style={circle,draw}]
      \node (r) {$r$}
      child { node (T1) {$T_1$} }
      child {node {$\ldots$}  edge from parent[draw=none]}
      child { node (Tn) {$T_n$} };
   \end{tikzpicture}
\end{document}

enter image description here

Edit (2): Thank to @cfr, which pointed me to simple solution: your line

child { edge from parent[draw=none] node[draw=none] (ellipsis) {$\ldots$} }

reorder to 

 child {node[draw=none] {$\ldots$} edge from parent[draw=none]}

and you will get desired results. Deep explanation you can find in cfr answer. It is very instructive.

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