# How does one use \node[inner node]{}?

I'm trying to reproduce a TikZ tree from a Till Tantau presentation (see pg.33 of this .pdf)

My code is as follows:

    \documentclass{article}

\usepackage[latin1]{inputenc}
\usepackage{tikz}
\usetikzlibrary{trees}
\begin{document}

\begin{tikzpicture}[edge from parent fork down, edge from parent/.style={black,thick,draw}]

\node[inner node]{}
child { node {bacteria} }
child {  node[inner node] {}
child { node {plants} }
child   { node[inner node] {}
child { node[inner node] {}
child { node {fish} }
child { node[inner node] {}
child { node {mammals} }
child { node {birds} }
}
}
child { node[inner node] {}
child { node {dragonflies} }
child { node {beetles} }
}
}
};

\end{tikzpicture}

\end{document}


I get six errors of the type below for each of the six node[inner node] {} calls in the code above:

    ! Package pgfkeys Error: I do not know the key '/tikz/inner node' and I am goin
g to ignore it. Perhaps you misspelled it.
See the pgfkeys package documentation for explanation.
Type H <return> for immediate help.
...
l.11 \node[inner node]
{}
This error message was generated by an \errmessage
command, so I can't give any explicit help.
Pretend that you're Hercule Poirot: Examine all clues,
and deduce the truth by order and method.


I couldn't find anyting pertinent on this type of usage in the PGF manual. Any help is welcome!

-
Which version of PGF are you using? –  Loop Space Sep 15 '11 at 15:52
inner node is the name of a node with a matrix but it's not a style with PGF 2.10 CVS. –  Alain Matthes Sep 15 '11 at 18:40
I get a similar error message with TeXLive2011 (updated within the last week)... –  Peter Grill Sep 15 '11 at 20:28
I use PGF 2.0 which is available as a debian package under Ubuntu 11.04 –  champost Sep 15 '11 at 22:15

I think that the presentation of Till Tantau does not really define the inner node style. I have the impression that he just wanted to illustrate that one can provide "some kind of options".

You can write

\begin{tikzpicture}[....,inner node/.style={fill,black,circle}]


to define it somehow. I tried to reproduce some filled dot, try out if this is what you want. If not, you may want to experiment with out tikz options.

-
The source code for the presentation can also be found online. The complete source for the tree (including how to draw it that way sideways) can be found starting from line 940 in main.tex. –  Caramdir Sep 15 '11 at 21:43
Ok, I get it now. What I initially wanted was a filled black circle at the end of each edge of the tree like in Till Tantau's figure. The above code puts it somewhere in the middle. I tried using node[at end] without much success... –  champost Sep 15 '11 at 22:36
@Caramdir Exactly what I needed. Now I'm learning PGF by leaps and bounds... –  champost Sep 15 '11 at 22:52