You've got some bamboo there, but I'd say it's a not River Cane (Arundinaria gigantea), but some other species gone wild. True River Cane doesn't get more than about an inch in diameter and normally grows to less than 30 ft tall.
That being said, in many ways bamboo is bamboo and will all work pretty much alike. However, like woods, there are some subtle and not so subtle differences between species, depending on what you want to do with it. As a freebie, it sure can't hurt to try and baking backing out of it! Split that 4" culm into strips about 2" wide and start sanding the inside until you get a nice flat surface. Leave the outside alone.
Once upon a time I made a bamboo backed and bellied bundle bow about 48" long with 1-1/2" wide bamboo strips simply lashed together. I epoxied and tied wooden tips on the ends for nocks. Worked pretty darn good - nice snappy cast to it.
Generally speaking you want to harvest 1-2 year old culms. Not the newest greenest growth, and not the old brown and dead culms.
