I think the problem is that proper iguana care in captivity has only been until very recent. Yes the diet has been for a while, yet proper UV lighting has not been around all to long considering. One thing for sure though, wild greens develop much taller spikes than any captive animal. Even large adult's that are captured end up with spikes that lay over. Regardless of how hard we try, being in the wild is the best care and typically produces the most stunning animals.