Acoustic Guitar Construction

I bought a back/side set of this wood online, looked attractive (and cheap) enough. When it arrived, the sides had a profusion of dark streaks along the grain. Vendor said, well, there's some of that in this wood, but after sending him some photographs he sent me a pair of replacement sides, with hardly a streak.

So...anybody know what these streaks are in this variety? Is this wood unusually sappy? Can the sides be worked to cause the streaks to go away? And how to do that? Assuming I can manage the streaks/stains, can anyone speak up about how this wood behaves in a bender?

Comments, observations, and suggestions are welcome, hoped for, even. And I'm afraid I can't post a picture, I need to go to the image-handling setup with a picture-storing site first. I'd be glad to email a picture to someone who sends me a PM with a return email address.

Thanks very much.

I would suggest that you take the time to learn to post images -- its really not very difficult and your forum participation will be much more rewarding. $.02