Cut fruit of Hana Yuzu
seeds from Hana Yuzu fruit
Potted Hana Yuzu
Hana Yuzu fruit close-up
The Yuzu is believed to be a hybrid of Citrus ichangensis and Citrus reticulata, and was formerly classified as Citrus junos. The Hana Yuzu variety is grown in Japan as an ornamental mainly for its especially beautiful and fragrant flowers.
....the  Flower Yuzu from Japan
As I only obtained my potted plant this spring, I can't yet vouch for the fragrance and the beauty of its flowers, but I can say that the fruit peel is very fragrant.
Fruits ripen yellow with a bumpy surface.
The peel separates easily from the juicy, yellow internal flesh which contains a number of large seeds. My first fruit shown here was 5 cms in diameter, weighed 33gms (2"/1.2oz).and contained 12 seeds - each over 1cm long. The juice and flesh was inedibly sour.
page created 24th November 2012
Also known as Hanayu or Issai-yuzu.

APRIL 2015: YUZU PLANTS AVAILABLE! (not Hana Yuzu)
I currently have a few potted specimens for sale - only for personal collection. Specially imported from a Sicilian citrus nursery, these are usually impossible to find in the UK.
See ebay offer here.