Posted: 17/12/2014 at 17:18
Gran..........my fault as I should have described it as Bamboogie did. Beschorneria yucc. is a type of Agave rather than a Yucca.
It flowers early summer ( I seem to remember mine having produced ripened seed by late summer ).
The Yuccas tend to flower later and, as you say, quite often provide a wonderful Autumn display........always a bit of a shock as they seem too "exotic" to be doing their thing at that time of year. A couple of gardens near me still have them in full bloom.
Still don't think that is what the OP has tho