POST an array from an HTML form without javascript

check this one out.

<input type="text" name="firstname">
<input type="text" name="lastname">
<input type="text" name="email">
<input type="text" name="address">

<input type="text" name="tree[tree1][fruit]">
<input type="text" name="tree[tree1][height]">

<input type="text" name="tree[tree2][fruit]">
<input type="text" name="tree[tree2][height]">

<input type="text" name="tree[tree3][fruit]">
<input type="text" name="tree[tree3][height]">

it should end up like this in the $_POST[] array (PHP format for easy visualization)

$_POST[] = array(
    'firstname'=>'value',
    'lastname'=>'value',
    'email'=>'value',
    'address'=>'value',
    'tree' => array(
        'tree1'=>array(
            'fruit'=>'value',
            'height'=>'value'
        ),
        'tree2'=>array(
            'fruit'=>'value',
            'height'=>'value'
        ),
        'tree3'=>array(
            'fruit'=>'value',
            'height'=>'value'
        )
    )
)