Gjbphp is right. You should to use separate layers (you dont have to, but it's just easier for you). But i'm sure you already knew that. Unless you're pretty new to photoshop. As for the reeds: They are most likely custom made (as it should be) and you can't find brushes(/shapes) to fit those exact ones. But speaking in general you can sure find some reed/plant shapes. But i think the best way to go would be to make your own. And I hope that that was the original question of yours (hope i understood you correctly, fingers crossed). And now that I have wasted plenty of your time explaining the obvious:
How to make some reeds:
They are most likely just some stroked paths combined (quite clever, yet simple, just as i like it). I hate using brushes/shapes someone else made.
This is a demo of how to create reed quickly (took me 7 mins, i was in a hurry so please don't judge the quality of my work by it). It consists of 7 steps.
Step 1: Create a nice blue gradient background.
Step 2: Create the ground, for the start a black square will do.
Step 3: Create a bunch of random smaller reed/weed and stuff. For this scrib around with brush tool (i used size 4 for the normal round brush) and erase away randomly. Continiue, when satisified.
Step 4: Start to create some larger stuff. For this i used once again size 4 brush. I created a path with "Paths" not "Shape Layers" options selected and stroked it. Then deleted the path.
Step 5: Continiue larger stuff. Same storke thing as before, but now with a size 9 brush.
Step 6 and 7: Just add some more details.
Final outcome
Hope this helps, if not don't be afraid to ask