Mary, I forgot to mention the myrmecophilous Whistling Thorns of Africa (e.g. Acacia drepanolobium) and South America (e.g. A. sphaerocephala). These have woody stipular spines which are hollowed out to form domatia inhabited by ants. The wind blowing over the entrance to the domatia causes a weird whistling sound. Regards. David Constantine drc@globalnet.co.uk