Question
i would like to plant a crape myrtle bush in my front yard. i need to know if they have a fairly shallow root system, which is what i need. if not can you recommend other bushes with shallow root systems?

Answer
Crape myrtle does have medium to deep roots, so I don't think it answers your needs.  However there are shrubs which have comparitively shallow roots:

Kolwitzia amabilis (The Beauty Bush)  has pink flowers in spring

Viburnum tinus has scented white flowers in late winter/early spring

Osmanthus delavay has scented white flowers in spring

Cercis silliquastrum has beautiful purple flowers in late summer

Rosmarinus officianalis (Rosemary)  has dark blue flowers in summer

Each of these shrubs have many varieties, but I have not specified any particular one as I don't know your needs regarding height, spread etc.

I hope you find something here to help with your choice of plant.

Gill