Technique for volumetric grass. Texturing question.

I'm working on generated, volumetric grass tiles. They are created during runtime from layers of quads with transparent textures :

(Ignore rear tiles, they are a different type of grass)

Right now just using a single quad prefab that gets generated multiple times vertically, for each tile. Each layer texture is identical, with alpha cutoff decreasing based on height.

The problem:

Limited to two dimensions of detail. A plan for 3D grass is to use layers of different textures to create a false 3D object.

A grass model sliced into 100 layers :

This code is attached to the root tile object and generates the layers :

     // Input values
     public GameObject grassLayer;
     public float patchHeight;
     public int layerCount;
     public float cutoffMin;
     public float cutoffMax;
 
     private float x, y, z;
     private float layerSep;
     private Renderer rend;
     
     void Start() {
         layerSep = patchHeight / layerCount;
         for (int i = 0; i < layerCount; i++) {
             x = transform.position.x;
             y = layerSep + i/(1/layerSep);
             z = transform.position.z;
 
             // Create/name/inherit grass layers
             GameObject go = (GameObject) Instantiate (grassLayer,
                                                   new Vector3 (x, y, z),
                                                   Quaternion.Euler (90, 0, 0));
             go.name = string.Format ("layer{0}", i);
             go.transform.parent = transform;
 
             // Set material parameters
             rend = go.GetComponent<Renderer>();
             rend.material.shader = Shader.Find("Legacy Shaders/Transparent/Cutout/Diffuse");
             rend.material.SetFloat("_Cutoff", (cutoffMax/layerCount) * i + cutoffMin);
             
         }
     }

What is a good method for creating 100 materials with unique texture that can be using for all grass tiles generated?