Another feature structure with LaTex

This is really just me playing around with LaTeX. By the way, for now I'm doing this on my sandbox on Wikipedia. I've downloaded some LaTeX tools, but I'll have to ask somebody here how to use them. Anyhow, here's the feature structure for the word defendants. The code is below.

And here's a pretty tree:

The alignment still isn't right. Any suggestions for fixing it are welcome.

Code

<math>
\left\langle
  \mathrm{defendants},
  \begin{bmatrix}
    word \\
    \mathrm{HEAD} &
      \begin{bmatrix}
        noun \\
        \mathrm{AGR} &
          \begin{bmatrix}
            \mathrm{COMPS} & pl \\
            \mathrm{PERS} & 3rd \\
          \end{bmatrix} \\
      \end{bmatrix}\\
    \mathrm{VAL} &
      \begin{bmatrix}
        val-cat \\
        \mathrm{COMPS} & \mathrm{itr} \\
        \mathrm{SPR} & -
      \end{bmatrix}
  \end{bmatrix}
\right\rangle
</math>