Hi,
I've used lemonwood for several bows, and it's fantastic stuff. It has such straight grain, that it almost has no grain at all. The growth rings are usually wide, and sometimes it's hard to tell grain orientation.
It is an excellent belly wood, excelling at compression. Hickory backed lemonwood is a great combination. It takes little set, and works well. It has a pale yellowish color, hence the name. It is a little difficult to obtain, however.
English longbowyers, like Pip Bickerstaffe, use hickory backed lemonwood glue-ups to make beautiful traditional ELBs with horn nocks. I have one, and I love it.
If you can get your hands on it, go for it... it's great stuff. I believe it is even better than hickory, especially for belly wood.