I had an old project created in AE4 or maybe AE3.5 that used a ramp and a wiggled displacement map to move around wheat grass.
You could set up your project like this.
layer 1 - Pre-composed solid with radial ramp applied, center 50% grey, outside white, center point at the stem of the bamboo leaf, visibility set to off.
Layer 2 - Footage layer with a single bamboo image, Displacement Map applied, 2 keyframes in the timeline for Horizontal and Vertical displacement amount and then apply the expression wiggle(5, 30) to each property. This will wiggle the horizontal and vertical displacement 30 pixels 5 times per second. Adjust the values to suit.
Now duplicate the bamboo layer as many times as you want and arrange to get the look you want. If you move the anchor point to line up with the center of the radial ramp then you'll be able to rotate and position the leaves to get the effect you're looking for.
I hope this helps. If I get a chance to look for the old wheat project I'll post it.
What are they based on? Photos? Graphic artwork? singular stems or a full bush? In case of photos of single stems, they might always look somewhat robotic simply because the lighting won't match as you move/ displace the footage. In that case you probably will have more luck by building your own graphics e.g. using shape layers, layer styles etc.. For a bush, Rick's suggestion of using dispalcement maps to rustle the leaves and add a soft generic sway might work. These days you could of course also use the Puppet tool to good effect in both scenarios. One other effect you might consider is Bezier Warp.
This simple example took about 5 minutes. I used a single instance of the bamboo leaves, applied the displacement map with the center of a radial gradient placed at the base of the stem, then rotated and moved copies of the displaced leaf to make the arrangement.
It's not perfect, it could be improved by a different gradient, and it could also be accomplished with puppet tools. The biggest thing that this example does is demonstrate how you use multiple copies of an element to create a whole.