knots on bows. How inportant?

Just getting into the initial stages of trying a longbow. I am interested in the more primative selfwood bows atm but I am curious about knots in the wood. I have seen a few Yew bows (on the net and in life) which have some large ish knots and even holes in the bow. Yesterday I was playing with a Yew bow which had a decent hole in but otherwise seems fine. Looking at some of the Italian high altitude 'hardwood' yew, this seems similar and these are well regarded high pundage (war) bows. Should this be something I should be wary of, at my lowish powdages, or is this just part of the character of the bow. Must say it did make them look more characterful!!

Hazel makes a surprizingly good bow...The bow with it's bark left on (in the bow building forum too), which I thought was Birch, is I now believe, Hazel.
There is a lot of Hazel about which has been allowed to grow big enough for bow building. It used to be regularly coppiced, but these days much woodland management seems to be neglected. It is generally relatively knot free and straight, it splits nicely too.
I was put off Hazel by my bow making exploits as a kid, but I wasn't seasoning it and I was making them too narrow due to starting with too thin a stave (the classic kids mistake not realising you really want to start with a 5" plus stave).
I'm currently working on stave from the better half of that Hazel log.
Have fun
Del